Powered patient support apparatus

ABSTRACT

Powered patient support apparatuses—such as beds, cots, stretchers, or the like—include a plurality of user controls that allow a caregiver to control the steering and/or driving of one or more powered wheels from multiple different locations around the patient support apparatus (e.g. head end, foot end, and/or the sides). The control is carried out by force sensors that detect both an orientation of the applied forces and a magnitude of the applied forces. Translational and/or rotational movement is effectuated, depending upon the magnitude and direction of the forces, as well as the physical location of the applied force relative to a reference point on the support apparatus, such as the center. One or more object sensors may also be included in the support apparatus to assist in steering and/or navigating.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. provisional patent applicationSer. No. 61/702,316 filed Sep. 18, 2012 by applicants Donna-MarieRobertson et al. and entitled POWERED PATIENT SUPPORT APPARATUS, thecomplete disclosure of which is hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to patient support apparatuses—such as,but not limited to, beds, stretchers, cots, operating tables, and thelike—and more particularly to patient support apparatuses that have atleast one powered wheel to assist in the movement of the patient supportapparatus over a floor.

Patient support apparatuses are used in hospitals, nursing homes, andother healthcare facilities for both supporting patients within a roomor other location, as well as transporting patients between rooms and/orother locations. While most patient support apparatuses include one ormore wheels that allow the support apparatus to be wheeled from thefirst location to the second location, the weight and bulk of thepatient support apparatus—including the weight of the patient supportedthereon, can make it difficult for a caregiver to manually wheel thesupport apparatus from one location to another. This can be especiallydifficult when there are inclines in the floors of the healthcarefacility, or when there are long distances involved, or when the patientand/or the support apparatus are heavy. This difficulty can be furtherexacerbated when it is desirable to maneuver the patient supportapparatus into, or through, areas with little excess clearance, such asin elevators, rooms, or corridors, or when turning the patient supportapparatus around a corner, or steering it past obstacles.

In the past, powered patient support apparatuses have been provided thatinclude a powered wheel that is driven by a motor positioned on thepatient support apparatus. One such example is shown in U.S. Pat. No.6,752,224 issued to Hopper et al. In prior powered support apparatuses,the powered wheel responds to controls issued by a caregiver. In someinstances, the caregiver controls the powered wheel by one or morehandles positioned at an end of the patient support apparatus. When thecaregiver pushes forward on the handle, the powered wheel powers thesupport apparatus forward. Conversely, when the caregiver pulls back onthe handle, the powered wheel brakes or moves backward. A load cell, apotentiometer, or some other type of sensor may be used to sense theforward/backward pushing of the caregiver.

Despite the assistance of the powered wheel, prior art powered patientsupport apparatuses can still be difficult to use, and/or suffer fromother disadvantages.

SUMMARY OF THE INVENTION

Accordingly, the various aspects of the present invention providepowered patient support apparatuses with improved controls and/or otherfeatures that make the powered support apparatus easier to use, steer,and/or control. In some aspects, the patient support apparatus of thepresent invention provides improved movement control by providingmultiple touch points that enable the caregiver to move the apparatus inmultiple directions. That is, the caregiver can be positioned virtuallyanywhere around the perimeter of the patient support apparatus and,without having to change position vis-à-vis the support apparatus, he orshe can move the support apparatus in any direction. The patient supportapparatuses include motorized steerable wheels that are steered inaccordance with input from a user. The motor controls the steering ofone or more wheels to match the direction in which the user wishes thepatient control apparatus to move. The motorized steered wheels are thesame as the powered wheels that move the support apparatus in oneembodiment, while they are separate from the wheels that provide motiveforce to the support apparatus in another embodiment. By controlling notonly the powered movement of the wheels, but also the steering of thewheels, a caregiver or other person moving the support apparatus isbetter able to control, steer, and/or move the support apparatus intight spaces, around corners, and/or through narrow openings.

According to one aspect of the invention, a patient support apparatus isprovided that includes a base, a patient support deck, a first motor, asecond motor, a force sensing system, and a controller. The baseincludes a powered wheel and a steerable wheel. The support deck issupported by the base and is adapted to support a patient. The firstmotor provides power to the powered wheel, and the second motor providespowered steering assistance to the steerable wheel. The force sensingsystem is adapted to detect forces exerted by a user, and the controlleris adapted to control the first and second motors based upon informationreceived from the force sensing system.

According to another aspect of the invention, a patient supportapparatus is provided that includes a base, a patient support deck, afirst motor, a second motor, a user input, and a controller. The baseincludes a plurality of powered wheels and a plurality of steerablewheel. The patient support deck is supported by the base and is adaptedto support a patient. The first motor is adapted to provide power to atleast one of the powered wheels, and the second motor is adapted tosteer at least one of the steerable wheels. The controller controls thefirst and second motors based upon information received from the userinput whereby the first and second motors assist in moving and steeringthe patient support apparatus over a floor.

In some embodiments, the powered wheel(s) and the steerable wheel(s) arethe same wheel(s), while in other embodiments, they are differentwheels. The force sensing system includes one or more force sensors thatare mounted to one or more of the side rails of the patient supportapparatus, or to other locations. In some embodiments, there is a singleforce sensor mounted per side rail, while in other embodiments, thereare multiple force sensors mounted per side rail. Force sensors mayalso, or alternatively, be mounted the footboard and/or the headboard ofthe patient support apparatus, particularly if the patient supportapparatus is a bed, or other apparatus having a headboard or footboard.Regardless of where they are mounted, the force sensors are adapted todetermine both a magnitude and direction of force applied thereto, suchthat the controller steers the steerable wheel and powers the poweredwheel in a manner that is based upon the magnitude and direction sensedby the force sensors.

In some embodiments, a litter is supported on the base that supports orincludes the patient support deck. The force sensors are positioned todetect forces exerted in a generally horizontal orientation against thelitter, wherein the controller uses the force sensor readings todetermine both a magnitude and direction of the forces and to steer thesteerable wheel and power the powered wheel in a manner that is basedupon the determined magnitude and direction. In some embodiments, theforce sensor is positioned at a junction of the litter and one or moreheight adjustment mechanisms that raise and lower the height of thelitter, or the force sensor is positioned at the junction of one or moreof the height adjustment mechanisms and the base. In still otherembodiments, one or more force sensors are positioned at a junction of awheel and a mount for the wheel, wherein the force sensor is adapted todetect both a direction and a magnitude of any horizontal force betweenthe wheel and the wheel mount, and wherein the controller steers thesteerable wheel and powers the powered wheel in a manner that is basedupon the magnitude and direction detected by the force sensor.

In some embodiments, the controller senses whether the brake is turnedon or off. If the brake is turned on, the controller does not controlthe first and second motors, regardless of any forces sensed or anycontrol signals provided by the user input. However, if the brake isturned off, then the controller is configured to automatically respondto any force readings or other manipulations of the user input that areintended to control the movement of the patient support apparatus.

In any of the embodiments utilizing force sensors, the force sensors maybe, or include, one or more load cells positioned in any of thelocations described herein. Also, in any of the embodiments using forcesensors, the controller uses the force sensor readings from multipleforce sensors in order to determine how to steer and power the patientsupport apparatus. Depending upon the location of the force sensorsand/or the configuration of the patient support apparatus, thecontroller computes the difference between force sensor readings, orsums and/or otherwise combines the readings from multiple force sensors,including, but not limited to, calculating moments of force created withrespect to a center point or other reference on the support apparatus.In some instances, the multiple detected forces are forces exerted byeach hand of a single caregiver, while in other instances the multipledetected forces are forces exerted by multiple caregivers on the patientsupport apparatus.

The one or more steerable wheels may be located adjacent one or more ofthe corners of the patient support apparatus. In such instances, thepowered wheel or wheels may be located interior from the corners, orthey may also be located at one or more of the corners, or they may bethe same wheels as the steerable wheels. Still further, in someembodiments, there are two powered wheels that are coaxially aligned andthe steering is effectuated by rotating one of the wheels faster orslower than the other of the two coaxially aligned wheels.

The steerable wheels are configured to allow the patient supportapparatus to rotate about a center of rotation that is positionedoutside of the footprint of the patient support apparatus. Inembodiments where there are multiple steered wheels, one or more of thesteered wheels may be controlled by a first motor while one or more ofthe other steered wheels may be controlled by a second motor that isindependent of the first motor. In this manner, the wheels are able tobe steered to have different orientations than each other, therebyallowing—at least in some embodiments—the support apparatus to beAckermann steered. Such independent steering also allows—in someembodiments—tight cornering, particularly in situations where wheels atthe forward end of the support apparatus are steered independently fromwheels at the rearward end of the support apparatus.

In any of the embodiments described herein, the patient supportapparatus may be one of a bed, a stretcher, or a cot.

In any of the embodiments described herein, the patient supportapparatus is modifiable to further include one or more object sensorspositioned thereon that detect the presence and/or location of nearbyobjects. The detection of such objects is used for collision avoidanceor steering, as well as navigation and/or docking of the patient supportapparatus. In some embodiments, the detection of objects influences notonly the automatic steering of the support apparatus, but also the speedof the patient support apparatus. That is, depending upon the locationof the detect object(s), the controller not only changes direction, butalso change speeds. Indeed, in some embodiments, the controller is incommunication with a brake or brakes such that the speed of the patientsupport apparatus is actively decelerated, if desired.

According to still another embodiment, a method is provided forcontrolling the movement of a patient support apparatus having asteerable wheel and a powered wheel. The method includes providing auser input on the patient support apparatus that is adapted to detect amagnitude and direction of desired movement of the patient supportapparatus over a floor; providing a controller on the patient supportapparatus that is adapted to control steering of the steerable wheel andto control the power delivered to the powered wheel; steering thesteerable wheel in a manner based upon the direction of desired movementof the patient support apparatus; and supplying an amount of power tothe powered wheel that is based upon the magnitude of the desiredmovement.

In other embodiments, the method further includes providing an objectsensor positioned on the patient support apparatus, and steering thesteerable wheel in a manner based both upon the desired movement of thepatient support apparatus and information received from the objectsensor. The steering may include steering the steerable wheel so as toavoid an object detected by the object sensor even if the user inputdetects a desired direction of movement that would otherwise lead to acollision with the detected object. In addition, or alternatively, themethod may include steering a plurality of steerable wheels on thepatient support apparatus based upon information received from theobject sensor.

In still other embodiments, the method includes providing a plurality offorce sensors adapted to detect forces exerted by a caregiver, anddetermining from the force sensors the magnitude and direction ofdesired movement of the patient support apparatus. The method may alsoor alternatively include rotating and translating the patient supportapparatus in response to the force sensors. Still further, the variousmethod embodiments may include determining a first magnitude and firstdirection of force exerted by a first caregiver on a first side of thepatient support apparatus; determining a second magnitude and a seconddirection of force exerted by a second caregiver on a second side of thepatient support apparatus; and combining the first and second magnitudesand directions to determine the magnitude and direction of desiredmovement of the patient support apparatus.

According to yet another embodiment, a patient support apparatus isprovided that includes a base, a powered wheel, a steerable wheel, apatient support deck, a force sensing system, and a controller. Theforce sensing system is adapted to detect both a direction and amagnitude of forces applied by a user, and it is also adapted todetermine the location on the support apparatus of the applied forcesrelative to a reference location. The controller controls the poweredwheel and the steerable wheel in a manner that takes into account themagnitude, direction, and location of the applied forces.

In this embodiment, the controller takes into account the torque ormoment of force created by the applied forces based upon their locationrelative to a center point, center region, or other reference location.The responding movement of the support apparatus is to steer thesteerable wheel in a manner that follows or matches how the patientsupport apparatus would turn if it were subjected to only the appliedforces. That is, the controller drives the powered wheel in a mannerthat generally amplifies the applied forces. In some embodiments, thepowered wheel and steerable wheel are the same, while in otherembodiments, they are different.

According to yet another embodiment, a patient support apparatus isprovided that includes a base, a powered wheel, a steerable wheel, apatient support deck, a force sensing system, and a controller. Thesupport deck includes a head end, a foot end, and a pair of sides. Theforce sensing system is adapted to detect both a direction and amagnitude of forces applied by a user from a first control locationpositioned adjacent a first one of the head end, foot end, and thesides; and the force sensing system is further adapted to detect both adirection a magnitude of forces applied by a user from a second controllocation positioned adjacent a second one of the head end, foot end, andthe sides. The first control location is different from the secondcontrol location. The controller controls the powered wheel and thesteerable wheel based upon forces detected at both the first and secondcontrol locations.

In this embodiment, the controller may be further adapted to control thepowered wheel and the steerable wheel based upon forces detectedsimultaneously at the first and second control locations. The controlleralso steers the steerable wheel in a manner that follows how the patientsupport apparatus would turn if it were subjected to only the appliedforces at either or both of the first and second control locations. Thecontroller powers the powered wheel in a manner that generally amplifiesthe total applied forces at both the first and second control locations.The steerable and powered wheel may be the same wheel, or differentwheels.

Before the embodiments of the invention are explained in detail, it isto be understood that the invention is not limited to the details ofoperation or to the details of construction and the arrangement of thecomponents set forth in the following description or illustrated in thedrawings. The invention may be implemented in various other embodimentsand is capable of being practiced or being carried out in alternativeways not expressly disclosed herein. Also, it is to be understood thatthe phraseology and terminology used herein are for the purpose ofdescription and should not be regarded as limiting. The use of“including” and “comprising” and variations thereof is meant toencompass the items listed thereafter and equivalents thereof as well asadditional items and equivalents thereof. Further, enumeration may beused in the description of various embodiments. Unless otherwiseexpressly stated, the use of enumeration should not be construed aslimiting the invention to any specific order or number of components.Nor should the use of enumeration be construed as excluding from thescope of the invention any additional steps or components that might becombined with or into the enumerated steps or components.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side, elevational view of a patient support apparatus thatmay incorporate one or more aspects of the present invention;

FIG. 2 is a diagram of a first example of a control system for any ofthe patient support apparatus embodiments of the invention;

FIG. 3 is side, elevational view of another patient support apparatusincorporating aspects of the present invention;

FIG. 4 is a close-up view of one of the wheels of the support apparatusof FIG. 3;

FIG. 5 is a plan view diagram of a first wheel configuration that may beincorporated into any of the patient support apparatus embodimentsdescribed herein;

FIG. 6 is a plan view diagram of a second wheel configuration that maybe incorporated into any of the patient support apparatus embodimentsdescribed herein;

FIG. 7 is a plan view diagram of a third wheel configuration that may beincorporated into any of the patient support apparatus embodimentsdescribed herein;

FIG. 8 is a plan view diagram of a fourth wheel configuration that maybe incorporated into any of the patient support apparatus embodimentsdescribed herein;

FIG. 9 is a plan view diagram of a fifth wheel configuration that may beincorporated into any of the patient support apparatus embodimentsdescribed herein;

FIG. 10 is a plan view diagram of a sixth wheel configuration that maybe incorporated into any of the patient support apparatus embodimentsdescribed herein;

FIG. 11 is a plan view diagram of a seventh wheel configuration that maybe incorporated into any of the patient support apparatus embodimentsdescribed herein;

FIG. 12 is a plan view diagram of a wheel configuration illustratingsome wheels being steered in opposite directions to other wheels, andwhich may be incorporated into any of the patient support apparatusembodiments described herein;

FIG. 13 is plan view diagram of a wheel configuration illustrating anAckermann steering configuration which may be incorporated into any ofthe patient support apparatus embodiments described herein;

FIG. 14 is a flow diagram of control logic that may be followed by acontroller incorporated into any of the patient support apparatusembodiments described herein;

FIG. 15 is a perspective view diagram of a patient support apparatuslitter illustrating force sensors that may be located at the junction ofthe litter and any one or more of a footboard, a headboard, and/or oneor more side rails, and which may be incorporated into any of thepatient support apparatus embodiments described herein;

FIG. 16 is a perspective view diagram of a patient support apparatusillustrating force sensors that may be located at the junction of thelitter and one or more height adjustment mechanisms for raising andlowering the litter, and which may be incorporated into any of thepatient support apparatus embodiments described herein;

FIG. 17 is a perspective view diagram of a patient support apparatusillustrating force sensors that may be located at the junction of thewheels and wheel mounts, and which may be incorporated into any of thepatient support apparatus embodiments described herein;

FIG. 18 is a plan view diagram of a patient support apparatus embodimentillustrating pure translation motion that may be implemented by acaregiver pushing on a side rail;

FIG. 19 is a plan view diagram of a patient support apparatus embodimentillustrating translation and rotational motion that may be implementedby a caregiver pushing and/or pulling with different forces on the endsof a side rail;

FIG. 20 is a plan view diagram of a patient support apparatus embodimentillustrating translation and rotational motion that may be implementedby multiple caregivers simultaneously pushing and/or pulling ondifferent side rails;

FIG. 21 is a plan view diagram of a patient support apparatus embodimentillustrating Ackermann steering that may be implemented by a caregiverpushing and/or pulling on a control at an end of the patient supportapparatus;

FIG. 22 is a plan view diagram of a caregiver controlling movement of apatient support apparatus embodiment via a side rail of the patientsupport apparatus;

FIG. 23 is a plan view diagram of a patient support apparatus embodimenthaving one or more sensors allowing the patient support apparatus toautomatically follow a walking caregiver positioned in front of thesupport apparatus;

FIG. 24 is a plan view diagram of a patient support apparatus embodimenthaving one or more sensors allowing the patient support apparatus toautomatically stay in front of a walking caregiver;

FIG. 25 is a plan view diagram of a patient support apparatus embodimenthaving one or more sensors allowing the patient support apparatus toautomatically assist in steering so as to avoid obstacles;

FIG. 26 is a plan view diagram of a patient support apparatusembodiments having one or more sensors allowing the patient supportapparatus to automatically steer tightly around corners so as tominimize the space occupied by the support apparatus during cornerturns;

FIG. 27 is a perspective view diagram of a patient support apparatusembodiment having one or more sensors allowing the patient supportapparatus to raise one or more wheels when traveling over a cord,threshold, or other discontinuity in the floor;

FIG. 28 is a plan view diagram of a patient support apparatusillustrating an auto-docking feature that may be incorporated into anyof the patient support apparatus embodiments discussed herein;

FIG. 29 is a plan view diagram of a patient support apparatus embodimentincorporating a plurality of sensors that enable the patient supportapparatus to automatically navigate without the need for human steering;

FIG. 30 is a plan view diagram of an arbitrary healthcare facility floorplan illustrating an example of automatic movement of the patientsupport apparatus of FIG. 29;

FIG. 31 is a perspective view of a patient support apparatus embodimenthaving a retractable and extendible platform for a caregiver to ride on;

FIG. 32 is a perspective view of a patient support apparatus mover thatmay be coupled and uncoupled to a patient support apparatus for movingthe support apparatus;

FIG. 33 is a perspective view of a patient support apparatus having nobuilt-in movement-across-the-floor capabilities;

FIG. 34 is a perspective view of the patient support apparatus of FIG.33 showing a mobile base that may be coupled to the support apparatus toallow the support apparatus to be moved and steered in a powered mannerover the floor; and

FIG. 35 is a diagram of a second example of a control system for any ofthe patient support apparatus embodiments of the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

A patient support apparatus 20 according to one embodiment is shown inFIG. 1. While the particular form of patient support apparatus 20illustrated in FIG. 1 is a bed, it will be understood that patientsupport apparatus 20 could, in different embodiments, be a cot, astretcher, a gurney, or any other structure capable of supporting apatient while being transported from one place to another.

In general, patient support apparatus 20 includes a base 22 having aplurality of wheels 24, a pair of elevation adjustment mechanisms 26supported on said base, a frame or litter 28 supported on said elevationadjustment mechanisms, and a patient support deck 30 supported on saidframe. Patient support apparatus 20 further includes a headboard 32 anda footboard 34.

Base 22 includes a brake that is adapted to selectively lock and unlockwheels 24 so that, when unlocked, patient support apparatus 20 may bewheeled to different locations. Elevation adjustment mechanisms 26 areadapted to raise and lower frame 28 with respect to base 22. Elevationadjustment mechanisms 26 may be hydraulic actuators, electric actuators,or any other suitable device for raising and lowering frame 28 withrespect to base 22. In some embodiments, elevation adjustment mechanisms26 are operable independently so that the orientation of frame 28 withrespect to base 22 can also be adjusted.

Frame 28 provides a structure for supporting patient support deck 30,headboard 32, and footboard 34. Patient support deck 30 is adapted toprovide a surface on which a mattress (not shown), or other soft cushionis positionable so that a patient may lie and/or sit thereon. Patientsupport deck 30 is made of a plurality of sections, some of which arepivotable about generally horizontal pivot axes. In the embodiment shownin FIG. 1, patient support deck 30 includes a head section 36, a seatsection 38, a thigh section 40, and a foot section 42. Head section 36,which is also sometimes referred to as a Fowler section, is pivotablebetween a generally horizontal orientation (not shown in FIG. 1) and aplurality of raised positions (one of which is shown in FIG. 1). Thighsection 40 and foot section 42 may also be pivotable, such as is shownin FIG. 1.

A plurality of side rails 44 (FIGS. 15-17) may also be coupled to frame28. If patient support apparatus 20 is a bed, there may be four suchside rails, one positioned at a left head end of frame 28, a secondpositioned at a left foot end of frame 28, a third positioned at a righthead end of frame 28, and a fourth positioned at a right foot end offrame 28. If patient support apparatus 20 is a stretcher or a cot, theremay be fewer side rails. In other embodiments, there may be no siderails on patient support apparatus 20. Regardless of the number of siderails, such side rails are movable between a raised position in whichthey block ingress and egress into and out of patient support apparatus20, and a lowered position in which they are not an obstacle to suchingress and egress.

The construction of any of base 22, elevation adjustment mechanisms 26,frame 28, patient support deck 30, headboard 32, footboard 34, and/orside rails 44 may take on any known or conventional design, such as, forexample, that disclosed in commonly assigned, U.S. Pat. No. 7,690,059issued to Lemire et al., and entitled HOSPITAL BED, the completedisclosure of which is incorporated herein by reference; or thatdisclosed in commonly assigned U.S. Pat. publication No. 2007/0163045filed by Becker et al. and entitled PATIENT HANDLING DEVICE INCLUDINGLOCAL STATUS INDICATION, ONE-TOUCH FOWLER ANGLE ADJUSTMENT, AND POWER-ONALARM CONFIGURATION, the complete disclosure of which is also herebyincorporated herein by reference. The construction of any of base 22,elevation adjustment mechanisms 26, frame 28, patient support deck 30,headboard 32, footboard 34 and/or the side rails may also take on formsdifferent from what is disclosed in the aforementioned patent and patentpublication.

Patient support apparatus 20 further includes one or more handles 46(FIG. 1) that are adapted to allow a caregiver to control poweredmovement of patient support apparatus 20. Handles 46 are pivotable abouta generally horizontal pivot axis 47 such that a user can pivot themforwardly with a forward force and pivot them backwardly with a rearwardforce. This pivoting is detected by one or more potentiometers, or othersensors, and used to control the powered movement of patient supportapparatus 20, as will be discussed in greater detail below. In someembodiments, handles 46 are located on or adjacent footboard 34, whilein other embodiments handles 46 are located on or adjacent headboard 32.

For purposes of the description provided herein, powered movement ofsupport apparatus 20 refers to movement of apparatus 20 in which one ormore motors, or other powered devices, supply at least some of the forceneeded for steering and/or moving apparatus 20 over the floor. Poweredmovement of patient support apparatus 20 therefore reduces the amount offorce a caregiver needs to exert to move the apparatus 20 from onelocation to another, thereby alleviating the work effort a caregiverneeds to expend during patient transport. In one aspect, patient supportapparatus 20 differs from prior powered patient support apparatuses inthat it provides powered steering in addition to, and/or in lieu of,powered movement. The provision of powered steering further reduces theworkload on a caregiver when moving apparatus 20.

In some embodiments, patient support apparatus 20 includes multiplehandles 46 positioned on or adjacent footboard 34 and/or on or adjacentheadboard 32. When multiple handles 46 are included, the poweredsteering of patient support apparatus 20 is implemented by analyzing thedifferent amounts of force exerted by a caregiver on the multiplehandles 46 and controlling the powered steering accordingly. Forexample, if a caregiver's left hand pushes strongly forward on a lefthandle 46, while a caregiver's right hand simultaneously pushes forwardwith a lesser force on a right handle 46, the patient support apparatuswill automatically turn one or more of the wheels 24 toward the rightbecause the caregiver's pushing forces suggest the caregiver wants toturn the support apparatus toward the right. That is, the patientsupport apparatus 20 steers the support apparatus generally in the samemanner that it would normally turn in response to the caregiver's forcesin the absence of any powered steering and/or powered movement. However,because of the inclusion of the powered movement and steering features,the amount of force required to be exerted by the caregiver to achievethe desired movement is lessened.

As will be discussed in greater detail below, the force sensors that arecoupled to handles 46 may include any one or more of load sensors,potentiometers, strain gauges, capacitive sensors, piezoresistive orpiezoelectric sensors, or any other types of sensors that are capable ofdetecting forces exerted by a caregiver. In many of the embodiments, theforce sensors will be configured to detect forces exerted in twomutually orthogonal generally horizontal directions. That is, forexample, the force sensors will be configured to detect exerted forcesthat have a component parallel to the longitudinal extent of apparatus20 (head to foot end), as well as forces that have a component parallelto the lateral extent of the apparatus 20 (side to side). In thismanner, the movement of patient support apparatus 20 can be coordinatedto match or align with not only the forward to backward forces exertedon the patient support apparatus, but also horizontal forces that aretransverse or oblique to the forward-backward axis of the patientsupport apparatus 20.

FIG. 2 illustrates in diagrammatic format one embodiment of a controlsystem 48 that is usable with any of the patient support apparatusembodiments discussed herein. Control system 48 includes a movementcontroller 50, a plurality of force sensors 52, one or more poweredwheel motors 54, and one or more steered wheel motors 56. Movementcontroller 50 can take on a variety of different forms, including one ormore microprocessors, microcontrollers, field programmable gate arrays,systems on a chip, volatile or nonvolatile memory, discrete circuitry,and/or other hardware, software, or firmware that is capable of carryingout the functions described herein, as would be known to one of ordinaryskill in the art. In general, movement controller 50 coordinates boththe steering and powering of one or more wheels 24 based uponinformation received from one or more force sensors 52, or from one ormore other user inputs. More specifically, movement controller 50receives electrical signals from the one or more force sensors 52,analyzes those signals, and outputs one or more commands to motors 54and 56 that cause the motors to operate in a manner that helps to movepatient support apparatus 20 in the direction desired by the caregiver.

As was noted above, force sensors 52 may include load cells,potentiometers, strain gauges, capacitive, piezoresistive orpiezoelectric sensors, or any other types of sensing structures that arecapable of detecting forces exerted by a caregiver thereon. Typicallysuch force sensors 52 are arranged or configured so as to detect any andall force components that are exerted in generally any horizontalorientation, or that have any horizontal components to them. Morespecifically, force sensors 52 are arranged to detect forces that aregenerally parallel to the horizontal plane defined by frame 28 ofpatient support apparatus 20, or the horizontal plane defined by wheels24 of patient support apparatus 20 (which may not be parallel to a truehorizontal plane if the support apparatus 20 is positioned on an inclineor decline, or other uneven ground). That is, force sensors 52 are ableto detect forces in both a lateral direction 66 and a longitudinaldirection 88 (FIG. 15). Force components that are vertically orientedwith respect to either of these planes may, in general, be ignored ornot sensed by force sensors 52, or used for other purposes besidescontrolling the movement of support apparatus 20 over the floor.

Force sensors 52 are able to not only detect the magnitude of forcesapplied, but also the direction(s) of those forces. And it will beunderstood by those skilled in the art, the reference to “direction” offorces herein will typically mean more than merely determining whether aforce was applied in a forward or backward direction. Rather, forcesensors 52 are capable of determining the direction of applied force ingenerally all horizontal, or approximately horizontal, directions. Thatis, force sensors 52 can detect any angular orientation, from zero tothree-hundred and sixty degrees, about a generally vertical axis,allowing the support apparatus 20 greater movement flexibility in thatit can be guided in more than just forward-reverse directions, but alsomany other directions as well.

Movement controller 50 is programmed, or otherwise configured, tocontrol powered wheel motors 54 and steered wheel motors 56 such thatthe wheels move in a manner based upon both the direction and magnitudeof forces exerted by a caregiver on the patient support apparatus 20, asdetected by force sensors 52. That is, movement controller generallysteers the wheels to either match the direction of the force or forcesexerted by a caregiver on force sensors 52, or rotates the supportapparatus 20 in a manner that corresponds to the torque on supportapparatus 20 that is created by the location of the applied force.Movement controller also powers the powered wheels in a manner that isat least somewhat related to the magnitude of the detected force orforces. The relationship between the magnitude of power supplied to thewheels and the magnitude of the detected forces may, in someembodiments, be a direct relationship, but also may be more nuanced thana simple direct relationship. For example, in some embodiments, movementcontroller 50 supplies power to the powered wheels in increments, ratherthan a continuous fashion. In still other embodiments, where multipleforce sensors 52 are detecting forces, the magnitudes of the detectedforces is used in determining steering, and the power supplied to thewheels is completely or partially independent from the force magnitudes.For example, in some embodiments, if two forces are applied to twodifferent sensors 52 with different magnitudes (or with differentdirections), the different magnitudes are interpreted by movementcontroller 50 to be indicating that the caregiver wants to turn thepatient support apparatus. In such cases, the detected force magnitudesinfluence steering commands issued by movement controller 50 more so, oras much as, the speed commands or power commands issued by movementcontroller 50 to powered wheel motor(s) 54.

FIGS. 3 and 4 illustrate an example of a patient support apparatus 20 ahaving different motors used for steering and for moving the apparatus20 a. As shown in FIG. 3, patient support apparatus 20 a includes fourwheels 24, which are each generally positioned adjacent the four cornersof apparatus 20 a. In this embodiment, each wheel 24 is both steerableand powered. FIG. 4 illustrates a close-up view of one of the wheels 24of FIG. 3. As can be seen, apparatus 20 a includes a steering motor 56positioned generally above its corresponding wheel 24. Steering motor 56is configured to rotate wheel 24 about a generally vertical axis 58based upon commands received from movement controller 50. Wheel 24 ofFIG. 4 further includes a power motor 54 that is located inside of wheel24 and that is configured to cause wheel 24 to rotate about a generallyhorizontal rotational axis 60. Power motor 54 gets its commands and/orelectrical power through a pair of cables 62 that connect thereto. Powermotor 54 rotates wheel 24 about axis 60 based upon speed or powercommands issued from movement controller 50. Each wheel 24 of patientsupport apparatus 20 a includes a corresponding power motor 54 and asteering motor 56. It will be understood, as described in greater detailbelow, that different embodiments of patient support apparatus 20 havedifferent arrangements and combinations of steerable and powered wheels.

FIGS. 5-13 illustrate a variety of different wheel configurations thatare able to be implemented in any of the patient support apparatusembodiments disclosed herein. In the various embodiments depicted inthese figures, wheels 24 that are powered (such as by a motor 54) willbe given the reference number 24 a; wheels that are steered (such as bya motor 56) will be given the reference number 24 b; wheels that areboth steered and powered will be given the reference number 24 c; andwheels that are neither driven nor steered will be given the referencenumber 24 d. In some instances, powered wheels 24 a are alternativelyreferred to as driven wheels 24 a. It will be understood that theembodiments depicted in FIGS. 5-13 are only several of many possiblewheel configurations that may be implemented, and that the location andcombination of powered and steered wheels can be modified from theexamples shown herein. It will also be understood that, for each of theembodiments shown in FIGS. 5-13, movement controller 50 will control thewheels 24 a, 24 b, and/or 24 c based upon signals received from one ormore force sensors 52, which are not shown in any of FIGS. 5-13. Thepotential location of force sensors 52 are described in more detail withrespect to FIGS. 15-17.

FIG. 5 illustrates a plan view diagram of a patient support apparatus 20b that includes four steered wheels 24 b positioned generally adjacenteach corner of patient support apparatus 20 b. In this embodiment, eachsteered wheel 24 b is steerable independently of the other three wheels24 b. Such independent steering is accomplished by providing foursteering motors 56 on patient support apparatus 20 b—one for each wheel24 b—or through other means. By providing independent steering of eachwheel, patient support apparatus 20 b may be rotated in smaller spacesthan a support apparatus that had fewer steered wheels. A powered wheel24 a is also provided in patient support apparatus 20 b and locatedgenerally near the center of the footprint of patient support apparatus20 b, although it may be offset somewhat toward either the front or rearends of apparatus 20 b. Powered wheel 24 a receives power from a motor54 that drives the wheel 24 a either forward or backward. In thisembodiment, powered wheel 24 a is not steerable, but instead only drivessupport apparatus 20 b either forward or backward, leaving wheels 24 bto handle the steering.

FIG. 6 illustrates a plan view diagram of another embodiment of apatient support apparatus 20 c that includes four steered and poweredwheels 24 c. Wheels 24 c are located generally near each corner ofpatient support apparatus 20 c, although, as with patient supportapparatus 20 b, these locations can be varied. Each of the wheels 24 cis both drivable and steerable independently from the other three wheels24 c. In the configuration shown in FIG. 6, patient support apparatus 20c has its wheels 24 c turned so that it can rotate about a center ofrotation 64 that is positioned outside of the footprint of patientsupport apparatus 20 c. Patient support apparatus 20 c includes fourseparate steering motors 56 and four separate driving motors 54 toachieve the independent steering and powering of each wheel 24 c. Insome embodiments, however, the driving and steering of wheels 24 c couldbe modified to be less independent. For example, the front wheels 24 ccould be driven as a pair (with the same power level) while the rearwheels 24 c could be driven as a separate pair (with the same powerlevel as each other, but not necessarily the same power level as thefront wheels 24 c). Other configurations of less independent poweringare also possible. Still further, some wheels could be steered intandem, or in other dependent configurations.

FIG. 7 illustrates a plan view diagram of another embodiment of apatient support apparatus 20 d that includes two driven wheels 24 a andfour wheels 24 d that are neither driven nor steered. Non-driven andnon-steered wheels 24 d may be castered wheels, or other free wheelingtypes of wheels. Patient support apparatus 20 d is configured to moveforward or backward by supplying equal power to both driven wheels 24 a.Patient support apparatus 20 d is further configured to provide steeringassistance by rotating one of wheels 24 a at a different rate than, orby applying a different amount of power to, the other of wheels 24 a.This difference in power or rotation rate exerts a turning force onsupport apparatus 20 d that can be controlled by movement controller 50based upon signals received from force sensors 52. In the embodimentshown in FIG. 7, wheels 24 are arranged side-by-side so that theirrespective rotational axes 60 are generally coaxial. It will beunderstood by those skilled in the art that the differential steering ofpatient support apparatus 20 d can be implemented with different poweredwheel arrangements, including arrangements in which wheels 24 a are notcoaxial.

FIG. 8 illustrates a plan view diagram of another embodiment of apatient support apparatus 20 e. Patient support apparatus 20 e differsfrom patient support apparatus 20 d in that the two driven wheels 24 ahave been replaced by two steered and driven wheels 24 c. Thus, patientsupport apparatus 20 e is not differentially steered, as support 20 dis, but instead has its steering controlled by rotating wheels 24 cabout their respective generally vertical axes 60, or about a commongenerally vertical axis. As with non-steered and non-driven wheels 24 dof patient support apparatus 20 d, wheels 24 d of apparatus 20 e arecastered or otherwise free wheeling wheels that rotate to match thecurrent direction of movement.

FIG. 9 illustrates a plan view diagram of another embodiment of apatient support apparatus 20 f. Patient support apparatus 20 f includesfour non-driven and non-steered wheels 24 d, as well as a sphericalwheel 24 e. Spherical wheel 24 e is shaped as a sphere and is controlledto roll in any desired direction. Further, spherical wheel 24 e isdriven in a controlled manner. Spherical wheel 24 e therefore providesboth a motive force for moving support apparatus 20 f and control overthe direction in which that motive force is applied to support apparatus20 f. In one embodiment, spherical wheel 24 e may be of the kinddisclosed in U.S. patent publication 2008/0084175 filed by Hollis andentitled Dynamic Balancing Mobile Robot. In this '175 patentpublication, the spherical wheel is identified by the reference numeral9. Other types of spherical wheels may also be used.

FIG. 10 illustrates a plan view diagram of another embodiment of apatient support apparatus 20 g. Patient support apparatus 20 g differsfrom patient support apparatus 20 f in that it includes a plurality ofspherical wheels 24 e. Spherical wheels 24 e of support apparatus 20 gmay be the same type of spherical wheels discussed above with respect topatient support apparatus 20 f. In at least one of the embodiments ofpatient support apparatus 20 g, both wheels 24 e are independentlycontrollable with respect to both direction and with respect to thepower or driving force that each exerts. By having a plurality of suchwheels 24 e, patient support apparatus 20 f can offer greater or bettermovement capabilities than support apparatus 20 f. For example, byrotating spherical wheels 24 e simultaneously in a lateral direction 66,it is possible to move patient support apparatus 20 g laterally withoutrotation. Further, by rotating spherical wheels 24 e in opposite lateraldirections (e.g. one wheel 24 e rotates parallel to direction 66 andtowards the right in FIG. 10 and the other wheel 24 e rotates parallelto direction 66 and towards the left in FIG. 10), it is possible torotate patient support apparatus 20 g about a center of rotation that ismidway between the spherical wheels 24 e. Further, by controlling therates or rotation, the location of the center of rotation 64 can bevaried.

FIG. 11 illustrates a plan view diagram of another embodiment of apatient support apparatus 20 h. Patient support apparatus 20 h includesfour non-steered and non-driven wheels 24 d positioned adjacent each ofthe four corners of support apparatus 20 h. Support apparatus 20 hfurther includes a driven and steered wheel 24 c that is positionedgenerally near the center of support apparatus 20 h. By controlling thedriving power supplied to wheel 24 c, as well as the direction it ispointed in, movement controller 50 can steer and move patient supportapparatus 20 h in a variety of different manners, including rotation andtranslational movement.

FIG. 12 illustrates a plan view diagram of another embodiment of apatient support apparatus 20 i, showing some additional structuraldetails of the support apparatus, including, for example, the side rails44 and head and foot boards 32 and 34. The inclusion of these side railsand head and foot boards in these drawings is in no way intended tosuggest that these components are, or should be, absent from theembodiments depicted in FIGS. 5-11, or in any of the other embodimentsthat omit these elements. Instead, these components have merely beenadded to provide additional graphical information about severalstructures that may be included in the various embodiments of thepatient support apparatuses described herein.

In the embodiment depicted in FIG. 12, patient support apparatus 20 ishows four wheels 24 that have been rotated to give the supportapparatus 20 i a center of rotation 64 that is located approximatelymidway between headboard 32 and footboard 34. The wheels 24 in FIG. 12have been given the generic reference number 24 because they are abletake on multiple different forms. That is, in one embodiment, they areboth driven and steered (e.g. wheels 24 c), while in at least one otherembodiment, they are steered but not driven (e.g. wheels 24 b). Whensteered, they are configured to allow movement controller 50 to controlthe steering of each one of them independently of the steering of theother three wheels.

FIG. 13 illustrates a plan view diagram of another embodiment of apatient support apparatus 20 j, showing the same additional structuraldetails as patient support apparatus 20 i. As with patient supportapparatus 20 i, the inclusion of the side rails, head, and foot boardsin this drawing is in no way intended to suggest that these componentsare, or should be, absent from the any of the other embodimentsdiscussed or shown herein.

Patient support apparatus 20 j of FIG. 13 is configured to implementAckermann steering. In this configuration, the two rear wheels are notonly non-steered, but they are fixedly attached to base 22 of supportapparatus 20 j in a manner that prevents them from turning aboutgenerally vertical axis 58, whether freely or by way of a steering motor56. In other words, the two rear wheels 24 are fixed similar to the tworear wheels of a conventional automobile. The two front wheels 24, incontrast, are both steerable. Further, they are steerable in a mannerthat enables them to trace out circles of different radii, therebyenabling them to avoid, or at least reduce, any side slippage whenturning. This Ackermann steering is controlled by movement controller50. In some embodiments, each front wheel 24 is controlled independentlywith no mechanical linkage, while in other embodiments a mechanicallinkage is coupled between the two front wheels 24 so that theirsteering is mechanically coordinated. When mechanically coordinated,movement controller 50 is configured to control only a single actuatorthat controls the mechanical linkage, whereas when no mechanical linkageis included, movement controller 50 controls two separate actuators ormotors for independently steering the front wheels 24.

FIG. 14 illustrates one example of an activation algorithm 68 used toactivate or deactivate (i.e. turn on and off) the powered movement ofany of the patient support apparatus embodiments disclosed herein. Thatis, activation algorithm controls whether or not one or more user inputs(which may be force sensors 52) will cause movement controller 50 tocontrol one or more of either driving motors 54 or steering motors 56.When not activated, a user's manipulation of the force sensors 52, orother types of user inputs, will not result in any operation of motors54 and 56. When activated, a user's manipulation of force sensors 52will cause movement controller 50 to activate one or more of motors 54and 56 in a manner that is dependent upon the specific user inputsignals that are received.

In the embodiment illustrated in FIG. 14, activation algorithm 68 ispartially dependent upon the presence or absence of a radio frequency(RF) identification (ID) tag worn by a clinician, or other authorizedcaregiver. Such RF ID tags are conventional RF ID tags that communicatewith corresponding detectors or sensors when the RF ID tag is positionedwithin a specific vicinity of the detector or sensor. In this case,patient support apparatus 20 includes an RF ID sensor 70 (FIG. 35) thatsenses any authorized RF ID tags that are within a vicinity of thesupport apparatus 20. The vicinity boundaries may vary, but in generalmay be configured to only detect RF ID tags that are within the sameroom as patient support apparatus 20, or within a section of the sameroom. On some occasions, the sensor 70 may detect RF ID tags that areoutside the room if they are positioned close to the doorway, but ingeneral it is desirable to not detect tags outside of the same room orarea that patient support apparatus 20 is currently located in.

If activation algorithm 68 detects the presence of an RF ID tag, thencontrol will transition to step 72. At step 72, patient supportapparatus 20 monitors whether or not any user inputs are detected ateither the side rails 44 of support apparatus 20, or at one of the endsof support apparatus 20 (e.g. at headboard 32 or footboard 34). If userinputs are detected at one or more of side rails 44, control passes tostep 74. If user inputs are detected at either or both of headboard 32and footboard 34, then control passes to step 76. When the controltransitions to step 74, movement controller 50 will respond to detecteduser inputs from the side rails 44 by either implementing a translationstep 78 or a steering step 80, or both, depending upon what specificinputs are detected at the side rail. If user inputs are detected onlyat one or both of the headboard 32 and/or footboard 34 (but not the siderails 44), then movement controller 50 will respond exclusively withsteering step 80.

Translation step 78 involves controlling either or both of drivingmotors 54 and steering motors 56 in a manner that enables supportapparatus 20 to move in lateral direction 66 without any rotation.Steering step 80 involves controller either or both of driving motors 54and steering motors 56 in a manner that will cause at least somerotation of support apparatus 20 about a generally vertical axis.Activation algorithm 68 will therefore allow only steering control whenusers are manipulating controls at either the head end or foot end ofpatient support apparatus 20, but will allow both steering andtranslational control when a user is manipulating controls at one ormore side rails 44.

If activation algorithm 68 does not detect the presence of an RF ID tagwithin close proximity to patient support apparatus 20, then controltransitions to state or step 82. State 82 is one of two states that willactivate a brake on patient support apparatus. The other state is state84, in which a user has pressed a brake button on patient supportapparatus 20, or otherwise turned such a brake on. Thus, in activationalgorithm 68, the brake will be activated (i.e. control will pass tobraking step 86) if either no RF ID tag is detected within closeproximity of support apparatus 20, or the brake is actively turned on bya user. When the brake is turned on, both motors 54 and 56 remain off.

In the illustrated embodiment, the steps of activation algorithm 68 arecarried out by movement controller 50, either alone or in combinationwith other components of support apparatus 20. In other embodiments,activation algorithm 68 may be carried out by other controllers onsupport apparatus 20. It will be understood by those skilled in the artthat many modifications to activation algorithm 68 may be made. Forexample, in one embodiment, the activation or de-activation of poweredmovement is controlled without any detection or regard to RF ID tags, orother types of tags worn by caregivers. In such an embodiment, patientsupport apparatus 20 includes a switch, button, or other control that,when activated, allows for powered movement to take place in response tothe manipulation of the corresponding user inputs (e.g. force sensors52). Such a switch, button, or other control may include a securityfeature, such as a code that needs to be entered, or other structurethat reduces the possibility of inadvertent or unknowing powering ofwheels 24 by individuals who had not intended to move patient supportapparatus 20. Alternatively, powered movement of patient supportapparatus 20 may automatically be enabled whenever the brake on supportapparatus 20 is turned off, and automatically disabled whenever thebrake is turned on. Still other variations are possible.

FIGS. 15-17 provide several illustrative examples of differentconfigurations and locations of force sensors 52. It will be understoodthat the several examples illustrated in these drawings are notexhaustive, and that variations from these configurations may be made.It will be further understood that the configurations shown in thesedrawings, and the modifications thereof, may be incorporated into any ofthe various patient support apparatuses 20 that are described herein.For example, the force sensor configuration shown in FIG. 15 could beimplemented on a patient support apparatus 20 having any of the wheelarrangements shown in FIGS. 3-13. Similarly, the force sensorsarrangements of FIGS. 16 and 17 could also be implemented on a patientsupport apparatus 20 having any of the wheel arrangements of FIGS. 3-13.Further, the activation and deactivation of any of the force sensorconfigurations of FIGS. 15-17 could be controlled by activationalgorithm 68, modifications to algorithm 68, or in still other manners.

FIG. 15 shows a frame or litter 28 of a patient support apparatus 20, aswell as several side rails 44 that are attached thereto. Still further,FIG. 15 shows a head board 32 and a footboard 34 that are attached toframe 28. Head board 32, footboard 34, and side rails 44 willcollectively be referred to herein as patient boundary structures. Inthe example shown in FIG. 15, each patient boundary structure is coupledto frame 28 by a pair of force sensors 52. In some embodiments, forcesensors 52 provide the physical coupling of the patient boundarystructures to frame 28, while in other embodiments force sensors 52 arecoupled to one or more separate structures that actually physicallysecure the patient boundary structures to frame 28. However arranged,force sensors 52 are coupled in a manner so that forces exerted by acaregiver or other user on any of the patient boundary structures aredetected by one or both of the force sensors 52 that are positioned atthe junction of that patient boundary structure and the frame 28. Thus,for example, if a user presses or pulls anywhere on footboard 34,including, but not limited to any one or more of locations A, B, and/orC, this pressing or pulling force will be detected by the force sensors52 a positioned at the junction of footboard 34 and frame 28. Further,any or all of force sensors 52 (including force sensors 52 a) may beconstructed so as to be able to detect forces exerted both in alongitudinal direction 88 as well as a lateral direction 66, althoughthis is not necessary.

Each of the force sensors 52 and 52 a in FIG. 15 are electricallycoupled to movement controller 50. This electrical coupling is direct,as shown in control system 48 of FIG. 2, although it may be indirect,such as through an embedded network, one example of which is shown inFIG. 35. However the force sensor readings are delivered to controller50, controller 50 processes those readings and outputs appropriatesteering and/or drive commands to motors 54 and/or 56 (assumingactivation algorithm 68, or some other activation mechanism, hasactivated the powered movement feature of the support apparatus 20). Insome embodiments, movement controller 50 control motors 54 and/or 56 sothat patient support apparatus 20 moves in a direction that generallycorresponds to how the patient support apparatus 20 would move inreaction to the applied forces if it were supported on frictionless ornear-frictionless ground-contacting spherical wheels, and it will movewith a speed or acceleration that generally corresponds to the magnitudeof the sensed forces. In other words, movement controller 50 attempts tocontrol motors 54 and 56 so as to mimic, but amplify, the motion ofpatient support 20 that would naturally occur as the result of theapplied forces. In this manner, the direction and magnitude of theuser's applied forces determine the movement of the support apparatus20, but the motors 54 and/or 56 supply all or a substantial portion ofthe energy needed to effectuate that movement so that the user's workeffort is reduced.

In amplifying the natural movement that would result from the forcesexerted by the caregiver, movement controller 50 takes into account notonly the direction and magnitude of forces applies to each force sensor52, but also the relative location of each force sensor 52 that issensing a force. These relative positions are defined with respect to areference location that is chosen by the manufacturer of the patientsupport apparatus. In some embodiments, the reference location is thegeometrical center of the patient support apparatus 20, while in otherembodiments the reference location is a vertical axis aligned with thecenter of gravity or center of mass of patient support apparatus 20,while in still other embodiments, some other reference position is used.

Thus, for example, if a user pushes forward on footboard 34 only atposition C, most of this force will be sensed by the right force sensor52 a (as shown in FIG. 15). A small amount of this forward force willalso be detected by left force sensor 52 a, depending upon theconstruction of footboard 34 and its connection to frame 28, (or even abackward force may be detected on left force sensor 52 a depending uponthe location of a possible pivot point of footboard 34). Regardless ofwhat the left force sensor 52 a detects, however, because thepredominant force will be sensed in a forward direction at a locationthat is located to the right of a center 90 of patient support apparatus20, movement controller 50 will control wheels 24 in such a manner so asto begin to turn support apparatus 20 leftward (as viewed in FIG. 15).This is because a forward force applied at location C that was greaterthan any forward force applied at any location on footboard 34 to theleft of center point 90 would naturally (i.e. without the use of motors54 and/or 56) tend to turn support apparatus leftward. Thus, movementcontroller 50 takes into account not only the direction and magnitudesof forces sensed by force sensors 52, but also takes into account whereeach of those force sensors 52 are located relative to a referencepoint, such as, but not limited to, center point 90. Stated in anotherway, movement controller 50 is configured to take into account theamount of torque that is applied by the sum of the sensed forces about agenerally vertical axis, such as one running through center point 90, orsome other point, and control motors 54 and/or 56 in a manner based onthis sensed torque.

Movement controller 50 takes into account the relative location of theapplied forces by retrieving from a memory on board the patient supportapparatus the location or locations of the one or more force sensors 52that are currently detecting applied forces. These locations are definedin a coordinate frame of reference that has its origin located atreference point 90 so that no additional calculations of the sensor'slocation relative to reference point 90 need to be made.

While the embodiment of FIG. 15 shows force sensors 52 positioned at thejunction of the side rails 44 and the frame 28, it will be understoodthat this location could be modified. For example, in one embodiment,force sensors 52 are mounted on the faces of any of the patient boundarystructures (e.g. side rails 44, headboard 32, and/or footboard 34),rather than at the interface or junction of these structures and theframe 28. When so mounted, a caregiver could apply force directly to theforce sensor 52, and forces applied to other locations of the patientboundary sensor would not be detected.

FIG. 16 shows a patient support apparatus 20 k having a configuration offorce sensors 52 a that are different from the configuration of FIG. 15.In the configuration shown in FIG. 16, there are two force sensors 52,both of which are capable of detecting forces in both lateral direction66 and longitudinal direction 88. Force sensors 52 of FIG. 15 arelocated at the junction of frame 28 and each of two height adjustmentmechanisms 26. By positioning force sensors 52 in this location, anyforces that are exerted in either lateral direction 66 or longitudinaldirection 88 on frame 28 will be detected by one or both of sensors 52.In other words, when someone exerts a generally horizontal force on anyportion of frame 28, including anything attached directly to frame 28(such as the patient boundary structures), that force will betransmitted to one or both of elevation adjustment mechanisms 26, whichsupport frame 28. However, because force sensors 52 are positioned atthe junction of frame 28 and these adjustment mechanisms 26, the forcesensors 52 will sense these forces.

The force sensor configuration of FIG. 16 has some advantages over theforce sensor configuration of FIG. 15. First, there are fewer forcesensors 52 required in the configuration of FIG. 16 than in theconfiguration of FIG. 15. The configuration of FIG. 15 may have up totwelve force sensors 52, while the configuration of FIG. 16 may have asfew as two force sensors 52. Having fewer force sensors 52 generallyreduces the cost of this configuration. Second, by placing force sensors52 at the junction of the elevation adjustment mechanisms and the frame,a person can exert a force anywhere on frame 28, not just on the patientboundary structures that are coupled to frame 28 (such as in theconfiguration of FIG. 15). If a caregiver is standing between two siderails 44, for example, he or she can push or pull directly on frame 28and have movement controller 50 respond in the corresponding manner.

As with the configuration of FIG. 15, movement controller 50 takes intoaccount—in addition to the direction and magnitude of forces sensed bysensors 52—the location of the force sensors 52 relative to a referencepoint on patient support apparatus 20, such as, but not limited to, thecenter point 90. Thus, if the two force sensors 52 were asymmetricallypositioned around center point 90, the detection of forces on bothsensors 52 of equal magnitude and direction would result in a torquebeing applied with respect to center point 90. Movement controller 50 isprogrammed to take into account such torque when determining how tocontrol steering motors 65 and/or driving motors 54. As was previouslynoted, center point 90 may be a geometrical center, or it may be acenter of mass, or some other center.

FIG. 17 illustrates another embodiment of a patient support apparatus 20l having yet a different possible configuration of force sensors 52. Inthis embodiment, force sensors 52 are integrated into, or coupled to,wheels 24, or mounted between the wheels 24 and the wheel supports. Aswith the other force sensors 52, the force sensors 52 of FIG. 17 areconfigured to detect forces in both the lateral and longitudinaldirections 66 and 88, respectively. These forces are forwarded tomovement controller 50 which processes them in the same manners as havebeen previously described. As with the configurations of FIGS. 15 and16, movement controller 50 for the support apparatus 20 l of FIG. 17takes into account the location of force sensors 52 relative to areference point when controlling motors 54 and/or 56.

FIGS. 15-17 illustrate several patient support apparatus embodimentswhere there are several control locations available to one or morecaregivers to control the powered movement of the support apparatus.These control locations include a head end control location 194, a footend control location 196, a right side head location 198, a right sidefoot location 200, a left side head location 202, and a left side footlocation 204 (FIGS. 18-21). A caregiver may stand in any of thesevarious locations and exert a force on the frame and/or patient boundarystructure. These exerted forces will then control, via movementcontroller 50, the movement of the patient support apparatus 20. Byhaving multiple control locations, it is easier for a caregiver toeffectuate powered movement of support apparatus 20 because he or shedoes not need to physically move to a single dedicated location forcontrolling such movement. This feature can be especially useful wherean end or side (or both) of support apparatus 20 is positioned upagainst a wall, or other obstacle, and a caregiver cannot easily standnext to the portion of patient support apparatus adjacent the obstacle.By having multiple control locations, however, a caregiver is assuredthat control of powered movement can be carried out in any convenientlocation.

FIGS. 18-22 illustrate various different types of forces that may beapplied at different positions to a patient support apparatus 20 andsensed by force sensors 52 (wherever located). The patient supportapparatuses 20 depicted in these drawings do not specifically identify atype of wheel configuration because they may include any of the wheelconfigurations of FIGS. 3-13, or still other configurations. Similarly,the location of the force sensors 52 may be same as in any of FIGS.15-17, or they may include still other force sensor locations andconfigurations.

FIG. 18 illustrates a situation in which a caregiver 94 located at theleft side head control location 202 is applying a purely translationalforce 92 to one of the side rails 44 of a patient support apparatus 20m. In this example, the force sensors 52 (not shown) will detect thispurely translational force and forward this detection to movementcontroller 50. Movement controller 50 will respond by controlling motors54 and/or 56 such that patient support apparatus 20 m will move withpurely translational motion in the direction of force 92.

FIG. 19 illustrates a different situation in which a caregiver 94 isapplying both a translational force 92 and a rotational force 96 to apatient support apparatus 20, which may be the same support apparatus 20m of FIG. 18, or it may be of a different configuration. Morespecifically, caregiver 94 is applying these forces to a side rail 44 ofpatient support apparatus. These translational and rotational forces aredetected by force sensors 52, which are configured in any of thepreviously described configurations, or still other configurations. Inresponse to these applied forces, movement controller 50 will move thepatient support apparatus so that it both translates and rotates.

FIG. 20 illustrates another situation in which a pair of caregivers 94are each applying a purely translational force 92, yet because thedirection of each purely translational force 92 is not the same, the netresult is to create a rotational force component in addition to atranslational force component. The cumulative translational force 100and cumulative rotational force 96 that result from the combination ofthe two translational forces 92 is shown in FIG. 20. This combinationtakes into account not only the direction and magnitude of thetranslational forces 92, but also their relative location to each otherand to a reference point, such as, but not limited to, center point 90.Movement controller 50 will respond to the cumulative rotational forcecomponent 98 and cumulative translational force component 100 bycontrolling motors 54 and/or 56 so that the patient support apparatus 20moves with a corresponding translational component and correspondingrotational component. The patient support apparatus 20 of FIG. is thesame as the support apparatus 20 m of FIG. 18, in one embodiment,although it will be understood that it may be different.

FIG. 21 shows yet another situation in which a caregiver is applyingboth a rotational force 96 and a translational force 92 to a foot end ofa patient support apparatus 20 n. In this embodiment of patient supportapparatus 20 n, the wheels 24 and movement controller 50 are configuredto implement Ackermann steering. The two wheels 24 toward the foot endof patient support apparatus 20 n therefore do not change direction,while the two wheels 24 toward the head end of patient support apparatus20 n are capable of changing direction. Based on the rotational andtranslational forces 96 and 92, respectively, applied by caregiver 94,movement controller 50 controls the steering of the two wheels 24 towardthe head end of the support apparatus 20 n so that they turn in adirection that corresponds to the rotational force 96. Movementcontroller 50 further drives any one or more of wheels 24 so thatsupport apparatus 20 n moves forward with a translational motioncomponent corresponding to translational force 92.

FIG. 22 shows an example of the path that a patient support apparatus 20might take under the control of movement controller 50 and the forcesapplied by a caregiver 94 to one of the side rails 44. Patient supportapparatus 20 of FIG. 22 starts in an initial position 102 where acaregiver is positioned adjacent a foot end side rail 44. After thecaregiver begins to exert forces on the side rail 44, which are sensedby appropriately positioned force sensors 52, patient support apparatus20 begins to both rotate and translate. This rotation and translationwill carry support apparatus 20 to an intermediate position 104, andeventually to a final position 106. In the final position 106, patientsupport apparatus 20 has rotated ninety degrees with respect to itsinitial position while the caregiver 94 did not need to repositionhimself or herself with respect to support apparatus 20. The simplemovement illustrated in FIG. 22 would not be possible with prior artpowered patient support apparatuses, which likely would have requiredeither multiple back and forth movements to move from initial position102 to final position 106, repositioning of the caregiver 94 atdifferent locations on support apparatus 20, and/or the use of a greateramount of space to make the transition from position 102 to position106. Thus, patient support apparatus 20 allows more efficient movementwith less space consumption. The patient support apparatus 20 of FIG. 22may be any of the various embodiments depicted herein, such as, forexample, any of patient support apparatuses 20 a-20 w, some of whichhave been described above and some of which will be described in moredetail below.

FIGS. 23-26 illustrate several other patient support apparatusembodiments that include one or more additional assisted navigationfeatures. Such assisted navigation features make it easier for acaregiver to control the movement of support apparatus 20. In thesupport apparatus embodiments of FIGS. 23-26, each patient supportapparatus 20 includes at least one object sensor 108 attached thereto.Object sensors 108 are any sensors that are capable of detectingobjects, obstacles, or other physical structures into which patientsupport apparatus 20 might collide with, bump into, or otherwiseundesirably contact during movement. Object sensors 108 thereforeinclude cameras, ultrasonic sensors, laser range finders, infraredprojectors and sensors, and any other sensor capable of detecting thelocation of one or more objects relative to support apparatus 20.

The patient support apparatus 200 of FIG. 23 includes an object sensor108 positioned at a head end of the support apparatus. Object sensor 108is positioned on any of headboard 32, frame 28, elevation adjustmentmechanism 26, or base 22, or integrated into any of these components. Inother embodiments, object sensor 108 includes multiple components, andthese components are dispersed amongst any of headboard 32, frame 28,elevation adjustment mechanism 26, and/or base 22. In the embodiment ofFIG. 23, the control system of patient support apparatus 20 o—which iscontrol system 48 (FIG. 2), or control system 110 (FIG. 35), or anyother suitable control system—is modified to include a “follow me” mode.The “follow me” mode allows the patient support apparatus 20 o toautomatically move and steer itself so as to follow behind an authorizedindividual, such as caregiver 94, as he or she walks. This isaccomplished by object sensor 108 detecting the location of thecaregiver 94 in front of support apparatus 20 o and movement controller50 issuing appropriate steering and driving commands to motors 56 and 54so as to cause support apparatus 20 o to follow behind the caregiver.Movement controller 50 controls the steering and driving of patientsupport apparatus 20 o in a closed loop manner that seeks to maintain aspecific distance, or range of distances, between support apparatus 20 oand caregiver 94. Object sensor 108 also detects the relative lateralposition of caregiver 94 with respect to the foot end of supportapparatus 20 o and movement controller 50 uses that information insteering support apparatus 200.

The “follow me” mode of patient support apparatus 20 o in FIG. 23 isturned on and off in any desirable manner. In some instances, there is aswitch, button, or other control positioned on one or more controlpanels of the patient support apparatus. In other instances, theactivation and deactivation of the “follow me” mode takes into accountthe presence or absence of an RF ID tag worn by caregiver 94. Forexample, in some instances, support apparatus 20 o is designed so thatthe “follow me” mode can only be used to follow individuals who arewearing RF ID tags, badges, or other authorized devices that can bedetected by one or more other sensors positioned on patient supportapparatus 200. This is accomplished by including one or more RF IDdetectors on the patient support apparatus 20 o that are able to detectwhen an RF ID tag is within the vicinity of patient support apparatus 20o—particularly in the front area of the patient support apparatus 20 owhere the tag-wearer will be positioned during the “follow me” mode—andhaving the internal circuitry on patient support apparatus 20 oautomatically switch on the “follow me” mode; or, alternatively, havingthe internal circuitry on patient support apparatus 20 o automaticallyprovide the option of turning on the “follow me” mode via one or more ofthe normal user interfaces included on the patient support apparatus200. In some embodiments, the detection of the RF ID tag is accomplishedthrough any of the near field detection techniques and systems disclosedin commonly assigned U.S. patent application Ser. No. 61/701,943 filedSep. 17, 2012 by applicants Mike Hayes et al. and entitled COMMUNICATIONSYSTEMS FOR PATIENT SUPPORT APPARATUSES, the complete disclosure ofwhich is hereby incorporated herein by reference. In other embodiments,other techniques and/or systems are used.

FIG. 24 illustrates another embodiment of a patient support apparatus 20p that includes a control system that is adapted to allow a user toselect a “hands free push” mode. The “hands free push” mode can beincorporated into a patient support apparatus 20 p that also has thecapability of the “follow me” mode (e.g. apparatus 200 of FIG. 23), orit can be incorporated into a patient support apparatus by itself. The“hands free push” mode is like the “follow me” mode, but reversed. Thatis, in the “hands free push” mode, movement controller 50 controlsmotors 54 and 56 so as to move support apparatus 20 p in a way thatstays ahead of caregiver 94, who is positioned behind support apparatus20 p. In carrying out this movement, movement controller 50 relies onsignals coming from an object sensor 108 positioned at the foot end ofsupport apparatus 20 p. This object sensor is positioned on footboard34, frame 28, elevation adjustment mechanism 26, or base 22, orintegrated into any of these components. In other embodiments, objectsensor 108 includes multiple components, and these components may bedispersed amongst any of footboard 34, frame 28, elevation adjustmentmechanism 26, and/or base 22. Based on the output of the object sensor108, movement controller 50 steers and drives patient support apparatus20 p in a manner that seeks to maintain a specific distance, or range ofdistances, between support apparatus 20 p and caregiver 94. In oneembodiment, object sensor 108 detects the relative lateral position ofcaregiver 94 with respect to the foot end of support apparatus 20 p andmovement controller 50 uses that information in steering supportapparatus 20 p.

The “hands free push” mode is turned on and off in any of the samemanners discussed above with respect to the “follow me mode,” or instill different manners. That is, there may be a switch, button, orother control positioned on one or more control panels of the patientsupport apparatus. The activation and deactivation of this mode mayalso, or alternatively, take into account the presence or absence of anRF ID tag worn by caregiver 94. For example, in some instances, supportapparatus 20 p is designed so that the “hands free push” mode is onlyaccessible to individuals who are wearing RF ID tags, badges, or otherauthorized devices that can be detected by one or more other sensorspositioned on patient support apparatus 20 p. As noted above, suchsensors are, in some embodiments, the same or similar to those disclosedin the commonly assigned U.S. application Ser. No. 61/701,943, which hasbeen incorporated herein by reference.

It will be understood by those skilled in the art that either or both ofthe “follow me” and “hands free push” modes illustrated in FIGS. 23 and24 can be incorporated, either individually, or in combination, into anyof the patient support apparatuses described herein, and that thesemodes are able to be implemented using any of the wheel configurationsand any of the force sensor configurations that are described herein.

FIG. 25 illustrates another embodiment of a patient support apparatus 20q that includes one or more object sensors 108 that are used to assistin the steering of support apparatus 20 q as it moves. Unlike theembodiments of FIGS. 23 and 24, the embodiment shown in FIG. 25 reliesupon forces exerted by a user (and detected by force sensors 52) toinitiate and provide most of the control for the movement of supportapparatus 20 q. However, unlike most of the previous support apparatusembodiments described above, the apparatus 20 q of FIG. 25 is configuredto allow signals from object sensor 108 to override, either partially orwholly, steering commands detected via force sensors 52. That is, thecontrol system of the support apparatus of FIG. 25 is configured tofollow and implement the steering and motion commands of a caregiveronly to the extent they do not cause, or likely lead to, a collisionwith any objects that are detectable by object sensor 108. If movementcontroller 50 determines that the user inputs are likely to lead to acollision—based on the outputs from object sensor 108—it automaticallytakes corrective measures. Such corrective measures include steering thesupport apparatus 20 q away from the detected object, slowing the speedof support apparatus 20 q, or a combination of the two.

In the example illustrated in FIG. 25, a caregiver 94 is shown exertinga forward translational force 92 on support apparatus 20 q. Movementcontroller 50 converts this forward translational force into speed andsteering commands that cause support apparatus 20 q to move forward inthe same direction as force 92. However, upon nearing walls 112, objectsensor 108 will detect the presence of walls 112, as well as the absenceof these walls in a doorway 114 defined between walls 112. Movementcontroller 50 will therefore steer patient support apparatus 20 q towarddoorway 114 despite the fact that caregiver 94 might continue to exert apurely translational force 92 that would otherwise direct supportapparatus 20 q into wall 112. In addition to steering support apparatus20 q toward doorway 114, controller 50 also decreases the speed ofsupport apparatus 20 q, as appropriate. Indeed, if movement controller50 determines from object sensor 108's readings that doorway 114 is toonarrow to fit through, controller 50 brings patient support apparatus 20q to a complete stop.

In an alternative embodiment, instead of changing the steering and/ordriving of one or more wheels 24, patient support apparatus 20 q of FIG.25 could be configured to merely issue an alert or other warning signalif object sensor 108 detects an object. Such an alert could be visual,aural, tactile, or any combination of these. By only providing such analert, the caregiver 94 would be made aware of the potential collision,but controller 50 would leave it up to the caregiver 94 to take theappropriate corrections to the speed and course of support apparatus 20q so as to avoid a collision. In addition to the alerts, supportapparatus 20 q could be configured to include a display that provided anindication where on patient support apparatus 20 q the likely collisionis going to occur, which is especially helpful when support apparatus 20q is bulky and/or otherwise obstructs the view of a caregiver positionedbehind it.

The steering assist feature illustrated in FIG. 25 can be implemented inany of the patient support apparatuses described herein. That is, it isusable with any of the wheel configurations described herein, and/orwith any of the force sensor configurations described herein. Further,it may also be incorporated into, if desired, a patient supportapparatus 20 that also includes one or both (or neither) of the “followme” and “hands free push” modes of FIGS. 23 and 24, respectively.

FIG. 26 illustrates another control algorithm or feature that may beincorporated into any of the patient support apparatuses 20 having oneor more object sensors 108. More specifically, FIG. 26 illustrates aturning feature that enables a caregiver 94 to tightly turn a firstpatient support apparatus 20 r about a corner. This is especiallyhelpful in situations where other obstacles are present, or in othertight spaces. For example, in the situation of FIG. 26, a second patientsupport apparatus 20 s is shown that would be an obstacle for turningsupport apparatus 20 r were it not able to tightly turn around corner116. In other words, to avoid a collision in the situation where supportapparatus 20 r was not equipped with a corner turning feature, eitherthe caregiver controlling support apparatus 20 k would have to waituntil support apparatus 20 s moved out of the way, or the caregivercontrolling support apparatus 20 k would have to wait until thecaregiver controlling support apparatus manipulated a wide corner turnthat would likely involve back and forth motion.

The corner turning feature of FIG. 26 includes not only sensing thelocation of a corner via object sensor 108, but also controlling thesteering of one or more wheels 24 so as to stay within a close distanceto corner 116 as support apparatus 20 r is moved. If patient supportapparatus 20 is equipped with a wheel configuration that allows one ormore forwardly positioned wheels 24 and one or more rearwardlypositioned wheels 24 to be steered independently of each other, thenmovement controller 50 will also utilize this steering capability tomore automatically effectuate a tighter turn than would otherwise bepossible without this capability.

FIG. 27 illustrates another embodiment of a patient support apparatus 20t that includes a wheel-raising feature adapted to mitigate jostling ofsupport apparatus 20 t, as well as the patient support thereon, whentraversing discontinuities in floor height, whether due to obstacles,such as a cord 118, or to other things. Support apparatus 20 t of FIG.27 includes an object sensor 108 that is positioned at an end of supportapparatus 20 t, and which is coupled to base 22 thereof (although itslocation can be varied). Regardless of the physical position of sensor108, it is adapted to detect objects and/or surface discontinuities thatpatient support apparatus 20 t might encounter as it moves. Objectsensor 108 is further adapted to be able to detect the size of theobject or floor discontinuity and communicate a signal with the sizeinformation to a wheel controller (not shown) that is able to lift oneor more wheels 24 as the support apparatus 20 t travels over theobstacle. Object sensor 108 is further adapted to detect the distance tothe object as support apparatus 20 t moves and to provide updates ofthis distance measurement to the wheel controller so that wheelcontroller can time the lifting of the one or more wheels 24 to coincidewith the actual passage over the object or discontinuity. By lifting thewheel, the jostling impact that might otherwise have occurred withoutthe wheel lifting is reduced or eliminated, thereby increase the comfortof the patient riding on patient support apparatus 20 t. The wheellifting feature of FIG. 27 may be incorporated into any of the patientsupport apparatuses 20 discussed herein, either alone or in anycombination with the other control features discussed herein.

FIG. 28 illustrates another patient support apparatus 20 u whichincludes a control system adapted to provide an auto-docking feature.The auto-docking feature automatically steers and moves patient supportapparatus 20 u into a preferred location, with a preferred orientation,within a given room. As shown in FIG. 28, a docked position 120 isdefined adjacent to a wall having a sensor or locating unit 122 mountedthereto. Support apparatus 20 u, in addition to one or more objectsensors 108, includes a sensor that is able to communicate with locatingunit 122 in a manner that allows support apparatus 20 u to determine itsrelative position within the room.

In some embodiments, support apparatus 20 u has all of the floor plans,or room plans, within a given facility stored within its memory andlocating unit 122 simply provides an indication of which room supportapparatus 20 u is currently located in. Once support apparatus 20 uknows which room it is positioned it, it retrieves from its memory thepreferred docking location 120 corresponding to that room. Uponactivation of the auto-docking feature by a caregiver, support apparatus20 u will maneuver itself into the docked position 120. This maneuveringmay require steering itself around other objects that are in the room.In order to accomplish this, one or more object sensors 108 areincorporated into support apparatus 20 u such that it can steer itselfto avoid the detected objects.

In other embodiments, support apparatus 20 u of FIG. 28 does not includeroom layouts stored in memory, but instead automatically guides itselfto the docked position 120 by appropriate communications with locatingunit 122. Such communications include any form of information sharingthat helps guide patient support apparatus 20 u to docking location 120.The commencement of the auto-docking operation is initiated by themanipulation of any suitable user control. As with the other controlfeatures disclosed herein, this auto-docking feature is able to beincorporated into any of the patient support apparatuses 20 discussedherein, either alone or in any combination with the other controlfeatures discussed herein.

FIGS. 29 and 30 illustrate another embodiment of a patient supportapparatus 20 v that includes an automated navigation feature. In thisembodiment, patient support apparatus 20 v is configured such that it isable to automatically navigate from a first location within a healthcarefacility to a second location within the healthcare facility, withoutthe need for a caregiver to steer or otherwise manipulate the supportapparatus 20 v. This feature enables the patient support apparatus 20 vto function, in some embodiments, with various features and capabilitiesthat are similar to conventional automatic guided vehicles used in thematerial handling industry. This feature further allows a caregiver toinput a destination into support apparatus 20 v and have the patienttransport thereto automatically without requiring a staff member toaccompany the patient during this transport. Alternatively, thecaregiver can accompany the patient during transport, but the caregiverwill be free from having to steer and push the support apparatus 20 v,and therefore can focus on other activities.

The automatic navigation of support apparatus 20 v of FIGS. 29 and 30may be accomplished in a variety of different manners. In oneembodiment, object sensors 108 are sufficient by themselves to enablesupport apparatus 20 v to steer itself down hallways and corridorswithout collision to thereby move support apparatus 20 v to the intendeddestination. In other embodiments, additional sensors are included onsupport apparatus 20 v that enable it to automatically navigate. Suchsensors include wheel encoders that monitor the number of rotations ofone or more wheels 24. This enables support apparatus 20 v to determinethe distance it has traveled. Further, by monitoring the difference inrotation counts between two encoders coupled to wheels 24 positioned onopposite sides of support apparatus 20 v, the turns of support apparatusare detected. Still further, encoders coupled to any one or more ofmotors 54 and 56 monitor the distance traveled and the direction of thattravel. Other sensors, such as gyroscopes, inertial reference units,accelerometers, and/or still other sensors can also be included toprovide additional navigational information.

In one embodiment, support apparatus 20 v includes a floor plan or map124 stored in its memory that identifies the layout of a floor orsection of a healthcare facility, including the location of the roomswithin that facility. In some embodiments, one or more landmarks arepositioned throughout the healthcare facility at fixed locations thatare detectable by support apparatus 20 v. The locations of theselandmarks are included in map 124 stored in the memory of supportapparatus 20 v. When support apparatus 20 v detects one or more of theselandmarks, it uses the detection of that one or more landmarks to updateits position by consulting the stored map, which indicates the locationof those landmarks within the healthcare facility.

FIG. 31 illustrates yet another embodiment of a patient supportapparatus 20 w. In the embodiment of FIG. 31, support apparatus 20 wincludes an extendable and retractable riding platform 128 that ispositioned at an end of support apparatus 20 w. Riding platform 128provides a platform on which a caregiver is able to stand whilemanipulating the movement of support apparatus. In the embodiment ofFIG. 31, support apparatus 20 w includes a pair of handles 46 that areused by a caregiver to control the movement of support apparatus 20 w.Handles 46 include one or more force sensors 52 positioned thereon, orthey make pivoting contact with one or more force sensors 52 as a usermanipulates them, or they use other devices for detecting the movementsdesired by a caregiver. One such other device includes potentiometersthat measure the amount of pivoting of handles 46 as a caregiver pushesor pulls back on them. The amount of this pivoting is forwarded tomovement controller 50, which implements the corresponding movementcommands to one or more motors 54/56.

A separate force sensor 52, or other type of sensor, is included in eachhandle 46 so that the amount of force applied, or pivoting implemented,by a user to each handle 46 is separately determined. By making separatereadings for each handle 46, movement controller 50 is able to determinein which manner, if any, the caregiver wishes to turn support apparatus20 w, and thereafter implement the appropriate commands to motors 54and/or 56.

Riding platform 128 is both extendable out of, and retractable into, aportion of base 22, or it is positioned within either a space definedbetween the top of base 22 and the bottom of frame 28, or a spacedefined between the bottom of base 22 and the floor on which supportapparatus 20 w is positioned. Riding platform 128 is either supported ina cantilevered fashion from underneath support apparatus 20 w, or itincludes one or more wheels positioned underneath it that ride on thefloor and help support the platform 128 when it is in the extendedposition. Riding platform 128 is able to be incorporated into any of thepatient support apparatus embodiments discussed herein.

FIG. 32 illustrates a rideable bed mover 130 that includes a pair ofretractable legs 132 that are retractable from a generally flat andextended position (shown in FIG. 32) to a generally upright and verticalposition. In the position shown in FIG. 32, legs 132 are inserted undera conventional patient support apparatus 20 that does not have poweredmovement capabilities and moved, by way of mover 130, from one locationto another. Bed mover 130 includes a platform 134 on which a caregiveris able to stand and ride during movement of bed mover 130. Platform 134may either be fixed, or it may be movable between an extended useposition (shown in FIG. 32), and a more compact non-use position. Afterlegs 132 of bed mover 130 are inserted underneath a patient supportapparatus 20, they are partially lifted upward so as to raise or tip aportion of the patient support apparatus 20, or they are otherwisepositioned so as to securely engage the patient support apparatus 20.The partial lifting or tipping is accomplished in any suitable manner.One or more structures may also be included on either of legs 132 forreleasably securing mover 130 to the patient support apparatus 20.

In some embodiments, the control of bed mover 130 is carried out in thesame manner as the control of any of the patient support apparatusesdescribed herein. That is, in some embodiments, bed mover 130 includesone or more force sensors 52, which are positioned at suitablelocation(s) thereon, such as, but not limited to, a handle 136 of mover130, or elsewhere. Such force sensors 52 are configured to detect both amagnitude and direction of one or more forces applied by a user andforward that information to a controller, such as movement controller50, or another controller. Based on that information, mover 130 providesautomatic driving and/or steering of its wheels 138 in order to guideit, and an associated patient support apparatus 20, to a new location.In some embodiments, mover 130 includes a plurality of wheels 138 thatare each independently steerable and drivable. In other embodiments,only a subset of the wheels 138 are drivable and/or steerable. Further,in some embodiments, the drivable and steerable wheels 138 are the same,while in others they are different.

In the embodiment shown in FIG. 32, mover 130 includes four wheels, apair of large wheels 138 and a pair of small wheel 140 that arepositioned underneath legs 132. In this embodiment, small wheels 140 areneither drivable nor steerable. Instead, the driving and steering isaccomplished through the control of large wheels 138. The steering oflarge wheels 138 is carried out by rotating each of the two large wheels138 at different speeds, or it is carried out by rotating the axis ofrotation of each wheel about a generally vertical axis.

In some embodiments, mover 130 includes a removable touch controller142, such as, but not limited to, a touch screen controller. Touchscreen controller 142 is, in one embodiment, a removable computer thatis able to be coupled to a patient support apparatus 20, such as isdescribed in greater detail in commonly assigned, copending U.S.provisional patent application Ser. No. 61/606,147 filed Mar. 2, 2012 byapplicants Cory Herbst and entitled PATIENT SUPPORT, the completedisclosure of which is hereby incorporated herein by reference.Controller 142 provides a user interface adapted to allow a user tocontrol one or more functions of patient support apparatus 20. In orderto accomplish this control, mover 130 includes an electrical connector(not shown) that plugs into a corresponding connector on supportapparatus 20 and allows commands and/or other electronic information tobe passed between mover 130 and patient support apparatus 20. In someembodiments, this connection is a wire or cable, while in otherembodiments, it is wireless. In still other embodiments, thecommunication connection is carried out by inductive coupling. Examplesof suitable inductive coupling structures and methods that can be usedwith mover 130 are disclosed in commonly assigned, copending U.S. patentapplication Ser. No. 13/296,656 filed Nov. 15, 2011 by applicants GuyLemire et al. and entitled Patient Support with Wireless Data and/orEnergy Transfer, the complete disclosure of which is hereby incorporatedherein by reference. Other types of inductive coupling may alternativelybe used.

FIGS. 33 and 34 illustrate another system and method for transportingpatient support apparatuses from one location to another. As shown inthese figures, a non-mobile patient support apparatus 150 is effectivelymade mobile by the temporary addition of a mobility base 152. Themobility base 152 includes a plurality of wheels 154, at least some ofwhich are powered and at least some of which are steered. One or moresteering motors 56 and/or driving motors 54 are included within base 152for steering and driving the wheels 154 of mobility base 152. Mobilitybase 152 includes a pair of elevation adjustment mechanisms or lifts 156that can be raised and lowered. In order to move a non-mobile supportapparatus 150, mobility base 152 is moved underneath the supportapparatus 150 in a lateral direction 158 (FIG. 34). The movement of base152 in this lateral direction 158 may be facilitated by having all fourwheels 154 steerable or freely rotatable so that base 152 can translatein a direction parallel to lateral direction 158, thereby allowing base152 to be rolled underneath support apparatus 150 from one of its sides.

Once positioned underneath support apparatus 150, the height of lifts156 is adjusted so that support apparatus 150 is lifted. Such liftingcauses a plurality of legs 160 of support apparatus 150 to disconnectwith the ground, which would otherwise prevent rolling movement of thecombined support apparatus 150 and base 152. The lifting and lowering oflifts 156 (and support apparatus 150 when positioned over base 152) isaccomplished via one or more pedals 162 positioned on base 152. Suchpedals are coupled to an electric motor, a hydraulic pump, or any othersuitable structures for raising and lowering lifts 156. Supportapparatus 150 may include a plurality of slots 164, or other structures,defined on its underside that releasably receive the upper section oflifts 156 so as to releasably secure support apparatus 150 to base 152.Such temporary securement should be sufficient to prevent supportapparatus 150 from tipping during movement of base 152.

The control of the movement of base 152 is carried out in any of avariety of different manners. In one embodiment, a separate controlunit, such as a touch screen controller 142, is provided thatcommunicates with base 152. The touch screen controller 142 isreleasably positionable anywhere on support apparatus 150, such as, butnot limited to, its headboard 32, its footboard 34, or any otherlocation thereon. A user then steers and powers base 152 by touching theappropriate icons, or other graphical controls, that appear on thescreen of touch screen controller 142. Touch screen controller 142communicates with base 152 over a wired connection or a wirelessconnection (including, but not limited to, the inductive connectionsdiscussed above).

In another embodiment, patient support apparatus 150 has a controlleralready integrated into it that controls base 152 when it is coupled tosupport apparatus 150. As with controller 142, the electrical connectionbetween this controller and base 152 is wired in some embodiments andwireless (including inductive coupling) in others. In still otherembodiments, patient support apparatus 150 has one or more force sensors52 built into it that communicate with base 152 and a movementcontroller 50 positioned thereon in order to control base 152 in any ofthe manners discussed above with respect to the various mobile patientsupport apparatuses 20. By utilizing mobility bases 152 that areseparate from non-mobile patient support apparatuses 20, a healthcareinstitution can reduce the expense of purchasing support apparatuses 20that are all mobile, but instead can purchase the less expensivenon-mobile support apparatuses 150 and a smaller number of mobilitybases 152.

FIG. 35 illustrates an alternative control system 110 that is able to beincorporated into any of the patient support apparatus 20 discussedherein. In this embodiment, movement controller 50 is connected to anon-board communication network 170 that is in electrical communicationwith a plurality of other controllers. Internal communications network170 can be a Controller Area Network (including CANOpen, DeviceNet, andother networks having a CAN physical and data link layer), a LONWorksnetwork, a Local Interconnect Network (LIN), a FireWire network, anEthernet, or any other known network for communicating messages betweenelectronic structures on patient support apparatus. It could also be aplurality of controllers connected by point-to-point communication, suchas, but not limited to, controllers connected by universal serial bus(USB) connections, I squared C connections, or other point-to-pointcommunication protocols. Internal communications network 170 includes anumber of controllers or internal nodes that are in communication witheach other over the internal network 170. In addition to movementcontroller 50, these include a footboard controller 172, a sensorcontroller 174, a scale system controller 176, a first side railcontroller 178, a second side rail controller 180, an interfacecontroller 182, and a headboard controller 184. Before describing infurther detail the structure and functions of these controllers, itshould be pointed out that fewer and/or more controllers could be usedwith network 170 than the specific ones illustrated. Further, in someembodiments, the functions of one or more controllers are combined intoother controllers, and/or the functionality of the controllers ischanged.

Each controller that communicates over internal communications network170 includes one or more microprocessors, microcontrollers, fieldprogrammable gate arrays, systems on a chip, volatile or nonvolatilememory, discrete circuitry, and/or other hardware, software, or firmwarethat is capable of carrying out the functions described herein, as wouldbe known to one of ordinary skill in the art. Side rail controllers 178and 180 are physically positioned inside of a pair of side rails 44,while headboard controller 184 and footboard controller 172 arepositioned inside of headboard 32 and footboard 34, respectively. Otherlocations for these controllers may also be implemented.

Each controller in FIG. 35 typically includes a circuit board thatcontains the electronics necessary for controlling a user interface, oneor more actuators, one or more sensors, and one or more other electricalcomponents. For example, side rail controllers 178 and 180, as well asfootboard controller 172, include one or more user controls 186. Theuser controls 186 include one or more buttons or switches, or the like,or they include a touch screen, or other device for allowing a patientor caregiver to control one or more aspects of patient support apparatus20. Such aspects include the pivoting of the patient support deck 30,the activation and deactivation of the brake, the control of a bed exitalarm system, the control of height adjustment mechanisms 26, and otherfeatures of the patient support apparatus 20.

Sensor controller 174 is shown to interact with one or more sensors,including, but not limited to, one or more object sensors 108 and one ormore RF ID sensors 70, both of which have been described previously andneed not be discussed further. Additional sensors may feed intocontroller 174, such as, but not limited to, one or more sensors fordetecting the activation of the brake, and/or angle sensors fordetecting the angular orientation of one or more components of supportapparatus 20, such as the head section 36 of support deck 30. Controller174 is responsible for processing the outputs of all of the sensors itcommunicates with and forwarding messages containing the sensedinformation to the network 170 for use by any of the other controllers.

Movement controller 50 is in communication with one or more drivingmotors 54 and one or more steering motors 56. Movement controller 50 isalso in communication with network 170 where it receives informationfrom the various force sensors 52 that are positioned on patient supportapparatus 20. As shown in the embodiment of FIG. 35, there may be aplurality of force sensors 52, and these force sensors 52 may be coupledto different controllers. For example, in the illustrated embodiment,there are one or more force sensors 52 that feed into footboardcontroller 172, one or more force sensors 52 that feed into first siderail controller 178, one or more force sensors 52 that feed into secondside rail controller 180, and one or more force sensors 52 that feedinto a headboard controller 184. These controllers receive the forcesensor outputs, process them accordingly, and forward them onto network170, where they are picked up by controller 50 and acted uponaccordingly (in one or more of the manners that have been previouslydescribed). In alternative embodiments, force sensors 52 feed directlyinto movement controller 50 (rather than via network 170), or forcesensors 52 all feed exclusively into only a single one of the manycontrollers, instead of the multiple controllers of FIG. 35, whereinthat single controller then forwards the information from all of theforce sensors 52 to controller 50 via network 170.

Network 170 may include, as noted, an interface controller 182 thatgenerally oversees communication between patient support apparatus 20and one or more off-board electronic devices. This communication iscontrolled via one or more transceivers 188 in electrical communicationwith controller 182. Transceivers 188 allow support apparatus 20 tocommunicate with bed mover 130, mobility base 152, and/or for any otherelectronic device that is separate from support apparatus 20. In someinstances, interface controller 182 may also control communicationsbetween patient support apparatus 20 and a healthcare computer network,such as a healthcare Ethernet, or other type of network. Interfacecontroller 182 may also control or oversee any of the communicationsdisclosed in commonly assigned U.S. patent application Ser. Nos.61/548,491, filed Oct. 18, 2011, by applicants Hayes et al., andentitled PATIENT SUPPORT APPARATUS WITH IN-ROOM DEVICE COMMUNICATION,and 61/640,138 filed Apr. 30, 2012, by applicants Hayes et al., andentitled PATIENT SUPPORT APPARATUS COMMUNICATION SYSTEMS, the completedisclosures of which are both hereby incorporated herein by reference

Scale system controller 176 is in communication with a plurality ofsensors, such as load cells 190, that are used for detecting patientweight and/or patient presence. The operation of the load cells, in oneembodiment, is in accord with the system disclosed in commonly assignedU.S. Pat. No. 5,276,432 issued to Travis and entitled PATIENT EXITDETECTION MECHANISM FOR HOSPITAL BED, the complete disclosure of whichis hereby incorporated herein by reference). The load cells 190, inaddition to detecting patient weight, are also able to be used—in oneembodiment—for controlling movement of one or more movable portions ofpatient support apparatus 20, such as is disclosed in commonly assignedU.S. patent application Ser. No. 13/767,943, filed Feb. 15, 2013, byapplicant Donna-Marie Robertson et al., and entitled PATIENT SUPPORTAPPARATUS AND CONTROLS THEREFOR, the complete disclosure of which isincorporated herein by reference.

It will be understood by those skilled in the art that, in all of theembodiments discussed herein, the sensing of forces by force sensors 52is carried out repetitively and/or continuously during the movement ofthe patient support apparatus. In some embodiments, this sensing offorces is performed multiple times per second. The information from therepetitive sensor readings is continuously or repetitively forwarded tomovement controller 50 in order to adjust, as necessary, the commandsissued to either or both of steering motor(s) 56 and driving motor(s)54. In this manner, the response to changing forces, as sensed bysensors 52, is updated many times a second so that movement of thesupport apparatus 20 will respond to changing applied forces. In someembodiments, the movement of patient support apparatus 20 is a closedloop control system based on the force inputs, while in otherembodiments the control is open loop.

In any of the embodiments discussed above where the patient supportapparatus is configured to provide both powered translational motion andpowered rotational motion, controller 50 makes the decision as to whichone of, or both of, these types of movements to effectuate based uponseveral different factors, depending upon the specific configuration ofthe patient support apparatus. In some embodiments, a speed sensor (notshown) is included that detects the speed of the movement of the patientsupport apparatus and this speed value is fed to controller 50. Basedupon the current speed of patient support apparatus 20, controller 50decides whether to apply translational forces, rotational forces, or acombination thereof, in response to the forces detected by the forcesensors 52. For example, in one embodiment, any detected force inputsfrom force sensors 52 will result in controller 50 causing purelytranslational motion of the support apparatus if the speed sensor(s)indicates that the support apparatus is currently traveling under athreshold speed. If the support apparatus is currently traveling at aspeed equal to, or faster than, the threshold speed, then any forcesdetected by force sensors 52 will be processed by controller 50 in amanner that causes powered rotation of the support apparatus to occur.The current speed of the patient support apparatus may alternatively beused in different manners to control whether translational or rotationalmotion is applied.

In still other embodiments, controller 50 will only allow lateraltranslational movement (i.e. in the direction of arrow 66 of FIG. 15) ifthe speed sensor(s) detect a current speed of the patient supportapparatus that is below the threshold, depending upon the configurationof force sensors 52 and the forces being applied to them. In otherwords, while the support apparatus is below the threshold speed,controller 50 supplies power to the motors 54 and/or 56 in any manner(lateral translation, longitudinal translation, and/or clockwise orcounterclockwise rotation), depending upon the forces applied by a userto force sensors 52. However, once the patient support apparatus meetsor exceeds the threshold speed limit, controller 50 only applies poweredmovement that effects longitudinal translation and/or clockwise orcounterclockwise rotation, and will exclude the possibility of lateraltranslation. In still other embodiments, the decision as to whetherdrive motors 54 and/or 56 in a manner that causes lateral translation,longitudinal translation (e.g. direction 88 of FIG. 15), or clockwise orcounterclockwise rotation is made without taking into account thecurrent speed of the support apparatus.

In one embodiment, controller 50 will direct motors 54 and/or 56 togenerate a purely lateral translation of support apparatus 20 only whenthe one or more force sensors 52 detect forces in the lateral direction(e.g. 66 of FIG. 15). In this embodiment, the controller 50 directsmotors 54 and/or 56 to provide longitudinal power when the magnitude anddirection of forces applied to at least two force sensors 52 are thesame, or have nearly the same direction and nearly the same magnitude.Further, in this embodiment, the controller 50 directs motors 54 and/or56 to rotate the support apparatus based upon the difference, if any, inthe magnitude and/or direction of forces applied to the two or moreforce sensors 52. Thus, for example, if a caregiver pushes forward on apair of force sensors 52 with generally the same magnitude, controller50 directs motors 54 and/or 56 to longitudinally translate the supportapparatus forward without rotation. If a caregiver pushes forward on oneforce sensor 52 and pulls backward on the other force sensor 52,controller 50 directs motors 54 and/or 56 to rotate the supportapparatus without either longitudinal or lateral translation (and thedirection of rotation will depend upon which force sensor is pushedforward and which is pulled backward). If the caregiver applies a purelylateral force to one or both of the force sensors 52, then controller 50directs motors 54 and/or 56 to effect a purely lateral translation ofthe patient support apparatus. Further, if mixtures of these forces areapplied, controller 50 applies the appropriate combination oftranslation and rotation. Thus, for example, if a caregiver pushesforward on both force sensors 52 but with magnitudes of force that aredifferent from each other by more than a threshold amount, controller 50controls motors 54 and/or 56 to apply both a forward longitudinaltranslation and some amount of rotation—the amount being dependent uponthe degree of difference in the magnitude of the applied forces.

In still other embodiments, the movement of the patient supportapparatus is controlled in yet other manners. As but one example, one ormore joysticks are added to the patient support apparatus. Controller 50reads the forces applied to the joystick and moves the patient supportapparatus accordingly. Such movement involves purely translationalmovement of the support apparatus in the direction corresponding to thedirection in which the joystick was pushed or pulled. Rotationalmovement is implemented, for example, only if the joystick itself istwisted (i.e. a rotational force was applied to it by a user that tendedto rotate the joystick about a generally vertical rotational axis).Still other implementations are possible.

Various additional alterations and changes can be made to any of theembodiments described herein without departing from the spirit andbroader aspects of the invention as defined in the appended claims,which are to be interpreted in accordance with the principles of patentlaw including the doctrine of equivalents. This disclosure is presentedfor illustrative purposes and should not be interpreted as an exhaustivedescription of all embodiments of the invention or to limit the scope ofthe claims to the specific elements illustrated or described inconnection with these embodiments. For example, and without limitation,any individual element(s) of the described invention may be replaced byalternative elements that provide substantially similar functionality orotherwise provide adequate operation. This includes, for example,presently known alternative elements, such as those that might becurrently known to one skilled in the art, and alternative elements thatmay be developed in the future, such as those that one skilled in theart might, upon development, recognize as an alternative. Further, thedisclosed embodiments include a plurality of features that are describedin concert and that might cooperatively provide a collection ofbenefits. The present invention is not limited to only those embodimentsthat include all of these features or that provide all of the statedbenefits, except to the extent otherwise expressly set forth in theissued claims. Any reference to claim elements in the singular, forexample, using the articles “a,” “an,” “the” or “said,” is not to beconstrued as limiting the element to the singular.

What is claimed is:
 1. A patient support apparatus comprising: a base; apowered wheel and a steerable wheel; a patient support deck supported bysaid base, said patient support deck adapted to support a patient; afirst motor adapted to provide power to said powered wheel; a secondmotor adapted to steer said steerable wheel; a litter supported on saidbase, said litter adapted to support said patient support deck; a forcesensing system positioned to detect forces exerted in a generallyhorizontal orientation against said litter at both a first location anda second location, said force sensing system configured to determineboth a magnitude and direction of any forces exerted against said litterat said first location and at said second location; and a controlleradapted to control said first and second motors based upon informationreceived from said force sensing system, wherein said controller steerssaid steerable wheel and powers said powered wheel in a first mannerthat is based upon said magnitude and direction of forces applied atsaid first location, and wherein said controller steers said steerablewheel and powers said powered wheel in a second manner that is basedupon said magnitude and direction of forces applied at said secondlocation, said second manner being different from said first manner. 2.The apparatus of claim 1 wherein said powered wheel and said steerablewheel are the same wheel.
 3. The apparatus of claim 1 further includinga plurality of side rails, and wherein said force sensing systemincludes a plurality of force sensors mounted to said plurality of siderails.
 4. The apparatus of claim 3 wherein said plurality of forcesensors are adapted to determine both a magnitude and direction of forceapplied thereto, said controller adapted to steer said steerable wheeland power said powered wheel in a manner that is based upon saidmagnitude and direction.
 5. The apparatus of claim 1 further including aplurality of height adjusting mechanisms positioned between said litterand said base, said height adjusting mechanisms adapted to change aheight of the litter relative to said base; and wherein said forcesensing system includes a force sensor positioned at a junction of saidlitter and one of said height adjusting mechanisms.
 6. The apparatus ofclaim 5 wherein said force sensing system includes a first force sensorpositioned at a junction of said litter and a first of said heightadjusting mechanisms, and a second force sensor positioned at a junctionof said litter and a second of said height adjusting mechanisms.
 7. Theapparatus of claim 1 further including a plurality of height adjustingmechanisms positioned between said litter and said base, said heightadjusting mechanisms adapted to change a height of the litter relativeto said base; and wherein said force sensing system includes a forcesensor positioned at a junction of said base and one of said heightadjusting mechanisms.
 8. The apparatus of claim 1 further including abrake, wherein said controller senses whether said brake is turned on oroff, and if said brake is turned on, said controller does not controlsaid first and second motors based upon information from said forcesensing system.
 9. The apparatus of claim 1 wherein said steerable wheelincludes said powered wheel and a second powered wheel having an axis ofrotation substantially coaxial with an axis or rotation of said poweredwheel, whereby rotation of said powered wheel and said second poweredwheel at different speeds imparts a rotational force on said patientsupport apparatus.
 10. The apparatus of claim 1 further including anobject sensor positioned on said patient support apparatus, saidcontroller further adapted to control said first and second motors basedupon information received from said object sensor.
 11. The apparatus ofclaim 1 wherein said patient support apparatus is one of a bed,stretcher, or cot.
 12. A patient support apparatus comprising: a base; apowered wheel and a steerable wheel; a patient support deck supported bysaid base, said patient support deck adapted to support a patient; afirst motor adapted to provide power to said powered wheel; a secondmotor adapted to steer said steerable wheel; a force sensing systemadapted to detect forces exerted by a user, said force sensing systemincluding a plurality of load cells positioned at a plurality oflocations that are adapted to detect both a magnitude and a direction ofa horizontal component of force applied by a user to said load cells;and a controller adapted to control said first and second motors basedupon the magnitude and direction of force applied by the user to theload cells, as well as the location of the load cells, whereby saidcontroller steers the steerable wheel and powers the powered wheel indifferent manners when forces are applied at different ones of thelocations.
 13. The apparatus of claim 12 wherein said patient supportapparatus is one of a bed, stretcher, or cot.
 14. A patient supportapparatus comprising: a base; a powered wheel and a steerable wheel; apatient support deck supported by said base, said patient support deckadapted to support a patient; a first motor adapted to provide power tosaid powered wheel; a second motor adapted to steer said steerablewheel; a force sensing system adapted to detect forces exerted by auser, said force sensing system including a first force sensor and asecond force sensor, both said first force sensor and said second forcesensor configured to detect horizontal forces applied to said patientsupport apparatus by a user; and a controller adapted to control saidfirst and second motors based upon information received from said forcesensing system, said controller adapted to steer said steerable wheelbased at least partially upon a difference between a force sensed bysaid first force sensor and a force sensed by said second force sensor.15. The apparatus of claim 14 wherein the first force sensor is adaptedto detect both a direction and a magnitude of forces applied by the userfrom a first control location and the second force sensor is adapted todetect both a direction and a magnitude of forces applied by the userfrom a second control location, said first control location differentfrom said second control location.
 16. The apparatus of claim 15 whereinsaid controller steers the steerable wheel in a manner that amplifieshow the patient support apparatus would turn if it were subjected toonly the applied forces at either or both of the first and secondcontrol locations.
 17. The apparatus of claim 15 wherein said patientsupport apparatus is one of a bed, stretcher, or cot.
 18. A patientsupport apparatus comprising: a base having a plurality of poweredwheels and a plurality of steerable wheels; a patient support decksupported by said base, said patient support deck adapted to support apatient; a litter supported on said base, said litter adapted to supportsaid patient support deck; a first motor adapted to provide power to atleast one of said powered wheels; a second motor adapted to steer atleast one of said steerable wheels; a user input; a controller adaptedto control said first and second motors based upon information receivedfrom said user input whereby said first and second motors assist inmoving and steering said patient support apparatus over a floor; and aforce sensor positioned to detect forces exerted in a generallyhorizontal orientation against said litter, said force sensor configuredto determine both a magnitude and direction of any forces exertedagainst said litter, wherein said controller steers said steerablewheels and powers said powered wheels in a manner that is based uponsaid magnitude and direction, and wherein said controller is adapted tocontrol said first and second motors in order to allow the patientsupport apparatus to be Ackermann steered.
 19. The apparatus of claim 18wherein said user input includes a force sensing system adapted todetect both a magnitude and direction of a force exerted by a user, andsaid controller is further adapted to control said first and said motorsin a manner based upon said magnitude and direction of force.
 20. Theapparatus of claim 19 wherein said user input is mounted to a side ofsaid patient support apparatus.
 21. The apparatus of claim 19 whereinsaid force sensing system includes a plurality of force sensors mountedto a side rail.
 22. The apparatus of claim 18 wherein said controller isadapted to be able to steer said steerable wheels such that said patientsupport apparatus rotates about a center of rotation that is positionedoutside of a footprint of said patient support apparatus.
 23. A patientsupport apparatus comprising: a base; a powered wheel and a steerablewheel; a patient support deck supported by said base, said patientsupport deck adapted to support a patient; a force sensing systemadapted to detect both a direction and a magnitude of forces applied bya user, said force sensing system further adapted to determine alocation on the patient support apparatus of the applied forces relativeto a reference location on the patient support apparatus; and acontroller adapted to control said powered wheel and said steerablewheel in a manner that takes into account the magnitude, direction, andlocation of the applied forces relative to the reference location,including any torque produced by the applied forces with respect to thereference location, said controller also steering the steerable wheel ina manner that amplifies how the patient support apparatus would turn ifit were subjected to only the applied forces.
 24. The apparatus of claim23 wherein the reference location is a center of gravity of said patientsupport apparatus.